Antisocial

Since high school, I have always felt like an outsider. I like different things than most people, I don't indulge in "fake" behaviors. I am what I am. I say what I feel and I mean what I say.
Lately I have been avoiding people even more than normal and it has me worried. I have been suffering with anxiety for a few years now. I think to some extent, I've always had it. I really would rather stay home than go out most of the time. I miss human interaction so I do go out, but groups of people really put me off.
I know a lot of it is insecurity. I wasn't the "cute" girl in HS. I only had one boyfriend in HS and he was gay (literally). I never fit in and I marched to my own tune even then.
What I am trying to sort out is whether I am doing something to make others dislike me, or whether I am just too "sensitive". Part of me really wants to know, but the other part of me wants to shut the door and be alone.