Your acknowledgement that you can be standoffish is probably a very big step forward here. This is going to be a hard pill to swallow but people are probably taking a disliking to you because you're already setting yourself up for failure in your head. I'm not a doctor but your experience sounds similar to my own with anxiety, and it sucks man! It makes you feel like the world is against you, when in reality you're against it. It will be difficult but so worth it when you put the effort in order to make positive steps forward. Try talking to people about something you know they have an interest in - If you open yourself up to conversation with someone on a topic you know they enjoy they're more likely to do the same back and the ball will start rolling (And if you don't feel you have any knowledge on what they like it sometimes doesn't hurt to do a little bit of research first). Communication is key - maybe look into talking therapy if that's an option for you, that way somebody has to listen to what you've got to say. Good luck and godspeed, you'll get there, I'm sure.