Adult here. The OP is going to need to look beyond his roommates for friends. Also, it’s quite possible that someone can like you and enjoy going out with you, and yet on another night or most nights they want to go out with another friend. I had friends in college that I liked but didn’t want to hang out with all the time or even very much. I still keep up with many of them. You’ve got to avoid the tendency that someone who is lonely sometimes has of finding a friend and wanting to latch on.
I’m not sure what dressing differently from everyone else means. I know what preppy is. But dressing differently to the point of looking odd can certainly create some distance and make things harder.
Concentrate on being a good student. Get out of your room to study. Attend various campus enrichment events such as special lectures, plays, concerts, etc.; don’t worry about going by yourself. I often did. Hopefully your activity will give you exposure to people that will enable you to create some friendships on varying levels, from casual friendship to closer friends. Just try not to rush it.
FWIW, even people who seem like everything is going great often have feelings of loneliness.