Congrats Justin for having the courage to go to a place you knew you may not be completely comfortable. As someone else who considers himself socially challenged, I'll give you what suggestions I can.
* Realize that many of the people around you may not be any more comfortable than you are. People are good at hiding their insecurities. I tend to compare my "insides" with other people's "outsides" assuming they are perfectly at ease when in reality they're having some of the same feelings I am but are hiding it well.
* I tend to assume everyone can tell I'm insecure and ill at ease. They can't, and even if they could, they are probably too focused on themselves to notice. I often feel I stand out when in reality no one notices.
* Before social events I've been telling myself "embrace the awkward". If I see someone who I don't know, I tell myself I will go talk to him/her. If there is an awkward moment because I don't know what to say or they seem less than thrilled to meet me, that's a good thing, because it means I'm trying. This has been working really well for me.
* Give yourself credit. I don't know if you're getting down on yourself because you expected more (or wished you'd done more) but if you are, change your self-talk to look for the positive. You went. You probably looked good and interesting, because people were interested.
* Next time before you go, work with a friend (or someone online from here) to come up with a few "talking points" things you can use to start a conversation. Local events that people might be interested in, the weather, sports, a movie that opened, election campaigns, whatever you think might be interesting. Practice some lines that might start a discussion, so when you see someone who seems interested, you have stuff to bring to the discussion.
Don't know if any of this is right for you, but I hope you can find one or two things to like. Take what you like and leave the rest. Good luck Justin.