FOMO or justified anxiety

Well hi there everyone. I did not anticipate being back so soon, but life has a funny way of working when you least expect it to. I have to say that I have become increasingly aware of my loneliness over the past few weeks and today it had reached a tipping point. I don't know if what I'm feeling is justified or if I'm just making up things in my head. I felt that it was necessary to type them out kind of as a therapeutic sorting of my thoughts. I guess you and I will both see if it helps. 
If you have looked over this website at all you will have discovered that I have lead somewhat of a nomadic life for the past three years. This has made it quite difficult to find/maintain friendships along the way. I've been told that I'm an outgoing, likable person and while I do tend to get along with people easily, it has been difficult for me to make the "all-in" best-friend friendships.
These friendships are the type where you can just go to them for everything, hangout and feel comfortable just being in each others presence. The person acts as your sounding board and support system while also accepting you in all your weird glory. You can count on them to be there and you in return are equally supportive, loyal, and present in their lives.  
Don't get me wrong I have had the fortune of having wonderful friendships in my lifetime. I appreciate all of them for the uniqueness that they bring to my life. I've just noticed that the more I move, the longer it takes for me to feel like I'm fully committed and all-in with the friends that I make. I have a difficult time allowing myself to be vulnerable with people and in return it has become difficult for me to create these deeper connections that I crave. 
Upon my most recent move I have fortunately had several people who have reached out and planted the seed of potential for these relationships. However, I being the socially anxious and non-initiator that I am, have had difficulty fully accepting these people into my life. At the same time I feel like while I am being accepted by these people it is not without conditions. 
Most of the friends I have created are friends that I work with. I see them Monday through Friday 8 AM-4 PM. Sure we share a passion for what we do and can find enjoyment in it, but this contributes to some of my anxiety when trying to find time to be actual friends with them outside of work. Some of the doubts and questions I find myself having include: "Did something I do at work irritate them today?" "Do they feel like they need a break from me because unfortunately I'm a coworker and my presence reminds them of work?" "They have significant others that they would like to spend time with and I don't want to insert myself into their couple time." It's giving me anxiety just to think about these issues as I write them out. So reader, am I simply just having a lot of anxiety over nothing and just need to take the initiative to suggest something or is there validation in the concerns that I have? 
Although a lot of the time I can convince myself that I'm being absurd and just overthinking the situation, there are situations which seem to justify my fears. For example, this past Friday one of my work friends was having a particularly rough day. With respect to her I won't provide details, but needless to say I did what I thought was best for her. I told her I was there if she needed anything both in person and via text. I sent her a quote that I thought might be comforting to her situation, and we made "plans" to get together later in the week (I put in quotation marks because nothing was solidified and I find that in these types of situations these things rarely follow through). 
She had told me that she needed to get away from life and that she had left with her boyfriend to go camping for the weekend. In my mind I was like yes, that is totally understandable, I would want an escape too. Unfortunately what I had  assumed about the situation was that this escape meant that her and her boyfriend were going together, alone for the weekend. 
Come this morning I find pictures on Facebook of not only her and her boyfriend, but several other couples that we are mutual friends with that  went on this camping trip as well. Now I'm not one to insert myself into others plans, but I can't deny that I felt a little hurt and left out with this discovery. When did her escape from reality turn into a couples retreat? If she needed to be away from everything why did it turn into a group event? And why, since it turned into a group outing was I not included?
Now don't get me wrong, I fully understand that sometimes things happen and maybe it turned into one of those situations where she was also talking to these other friends about what she was going through. Maybe they took a little more initiative than I did and were like, "Yeah, well I'm coming with you," or a "where are you going? We were planning on going camping and it would be fun to join you." Regardless of how things went down, do I have a right to feel slighted, left out, and forgotten?
To put this in a little perspective, since moving this friend is probably the closest I have come to being one of those 'ideal friendships'. However, I do feel myself holding back and not fully being able to commit myself to it in that way. I do this as a defense mechanism and don't allow myself to become fully invested as a way of protecting myself. At the same time I do care about her greatly and treat her the way I would treat any friend at any closeness level. While I feel that while she has accepted me and made an effort to be my friend, from my perspective it seems that I am still not quite on her priority list of people she would like to hangout with. 
Getting back to the situation at hand, the most realistic explanation I can think of is that there really was no reason I wasn't invited because things just kind of happened. So why can't I stop thinking that I'm somehow related to the cause of my exclusion? Why is it so difficult for me to accept that these guys were all friends before I got here and it's perfectly normal for them to get together and hangout as a group (sans me). 
The thing I think that gets me is that she said she needed an escape and I was willing to let her have one ,only to find out that she was 'escaping' with all of our other friends. Why did she need an escape from people if she was going to escape with people. 
One of the things I've discovered about being an adult is that making friends as an adult, is probably the hardest thing to do. A little ironic considering having friends is one of the most important things we need to have a good quality of life, but it is difficult. Even if you don't have the anxiety and other issues that I have, it is extremely troublesome to find new friends as an adult. One can't just go to a sandbox, play with all the other kids there while sharing our fruit snacks and end up with a play date a week from now. There aren't things like school to spark the growth of these relationships. If there is one thing I've learned about adulthood is that any relationship you create as an adult is strictly dependent on you and what you put out there. 
At this point in my life, I have a fair amount of people I consider friends. Several of whom I would consider close friends. What I don't have at the moment is a close friend within a 500 mile radius of where I'm currently residing. Situations like the ones I've discussed above and lack of taking the initiative to build those relationships has been a bit of a downfall for me each time I move somewhere new. I have been struggling with not having that type of friend lately and it is part of the reason why I've started this blog. 
Despite now having an outlet for all of the emotions and thoughts that I've been dealing with, I guess at the end of the day, I need to realize that if I want these close relationships with the people, I'm the one who needs to put in that extra effort and get over my own insecurities. I need to not let my emotions get out of hand and control my decisions/reactions.Truly the one thing that I really need to do is go out and create these experiences for myself.
I'll make a deal with you readers, I will make a minimum of two efforts a week to try to incorporate people into my life and within the next month give an update on how things have progressed in my social life. 
If you've made it this far you are a true trooper. Thank you and in return my challenge to you is to go make someone smile today. :) Until next time.
-Jordan