What's wrong with me?

It does not sound like there is anything wrong with you other then having an introverted personality trait. The only problem you may have is what can be called social awkwardness. I'm guessing from what you write that when you are around people you try to impress them with intelligence and that causes you to be alienated from some groups and when you are around others you try to be more casual with the same general affect. The best thing you can do is find a peer group that open accepts who you are. get a small group of people and enjoy things you like, if it is reading you can join a 3-4 person book club. the key to losing the social awkwardness you seem to have is to open up slowly to other and not feel that you have to be on guard and fear rejection if they don't see things the same way you do. Lastly i would say to stop trying to self diagnose because it tends to add to fears rather then help you overcome them.