If you are worried about roomies, you could try for a single? And I know I found a roomie who didn't drink by filling out the rooming survey the school sent out and in a facebook group for my graduating class. That is always an option. Rooming alone isn't a bad thing as long as you still socialize in class and stuff.
College is great if you let yourself enjoy it! There are pleanty of fun things to do that won't involve alcohol, because I know it makes me nervous too! My campus always has something going on.
Good luck and have fun. I think you will be just fine! Glad I could help.