Add me to the list of people who applaud you on what you have accomplished already! Good for you for recognizing your problem and dealing with it head on when others aren't always supportive around you.
I agree that you NEED to find some new friends. You don't necessarily need to replace the friends you have now, but you do have to add some sober friends to your circle. I really don't think spending your weekend cooped up watching movies solo is good for you. You need to find some sober people to do stuff with; bowling, skiing, gaming, even watching movies together. I promise you there are sober students doing things on weekends.
And I'm concerned that your gf isn't even 21 yrs old yet. I know you say she's not much of a drinker, but once she's legal and able to go clubbing and stuff, things might get harder for you rather than easier.
Hang in there. You really are doing an amazing job.