I actually kind of look like you.
I was pretty reclusive up until high school - then I started to join clubs and play sports. Since then I've disassociated myself from a lot of high school friends and tried to move on with my life.
College is a clean slate. First impressions mean everything (both ways).
Respect who you are. If small changes are necessary to help extend your good qualities, make them.
Just don't go overboard. I had some friends dye my hair once. Needless to say, they fucked up and I was the BUTT of many jokes until it grew out.
Try doing something you're interested in, even if you've never done it before. I'm sure your school has a vast selection of clubs to choose from. Like it was mentioned earlier, clubs and activities are great ways to socialize.
At worst, you can quit. Hey - at least you can say you tried.