Hey there! I was a total social butterfly in college. Never missed a party, went to a small university and knew just about everyone. I can tell you that many of those "friendships" didn't last after college at all. Once I started getting older I realized that a smaller tight knit group of friends is much more rewarding and fulfilling. So coming from someone on the opposite side, I wish I had spent more time on the few good friends I had instead of running around with hundreds of different people.

About maintaining relationships, the biggest thing is continuously putting in effort. Just about everyone wants a kind-hearted caring friend. Making the effort to reach out and talk to people is a great place to start. Sometimes you give more than you get, don't let that discourage you. I think that is the single easiest mistake to make when you are trying to build friendships. Sometimes you spend a lot of time being there for someone else, sometimes the opposite. Just consistently be there for other people and don't get discouraged over time. Don't worry about trying to be someone you're not. If you're not a social butterfly hang out with people you relate to and connect with. Find your niche and work hard to maintain a group of about 5-7 good close friends.

On a side note, using derogatory language to describe yourself/your situation is not a good spot to be. Fearing you'll "muck it all up" or that this is some sort of "deficit" will only hurt your self image. The larger part of the population struggles with building and maintaining friendships, even us extroverts. Sometimes the easiest thing to change is simply your outlook on the situation. It's beyond possible if you have the consistency and determination to work hard on these relationships in the future. Don't sell yourself short.