It's a problem if it's interfering with things you really want to do. There's nothing wrong with being an introvert--I don't like crowds, hate parties (especially work stuff) too. But 1 on 1 or very small groups with people I know, I do ok.
Definitely talk to your pdoc. It may be depression but it may be that you're lonely (and perhaps bored?) but if your feelings are keeping you from doing things you really want to do then please do check it out with a professional. You mentioned people can't be trusted--sounds like you've had some tough times in the past. It couldn't hurt to talk it over with a doc or a therapist.
Whatever you decide to do, we're rooting for you!