Of course you'll feel comfortable with the BF right now - but don't let him be the only highlight to your day. Trust, having friends + your BF is taking best of both worlds and purposely alienating yourself from getting to meet others will take that oppurtunity away from you.
I too get shy and uncomfortable around people I don't know and I hate to party (well, I just get uncomfortable when it's time to dance. ha) but when I started college, I realized my class became less fun and more boring without someone to be buddy-buddy with there and chat it up. So what I did, after a week or so - I weeded who seemed chilled and not annoying. The annoying ones seem to pop up within the week, funnily. And talk started with..."this class is/seems..." and then keep it going. I met really cool people by just being friendly and myself and trust me, I'm a super shy person but college has instilled within me the confidence to make new friends. And people will open up, remember - everyone new will feel the same way aswell...
The roommates, well - just because they drink doesnt mean you have to exclude yourself from them. My best friends are all partiers but they know I'm not into it, so they know not to invite me. Haha. Just let it be known it's not your scene and not because you're better than that but because you dont like it. Dont be a hermit and knock something down until you try it! Plus, you got a lock in your room... right? If you don't like it... stay on MUT. Haha.