I commend you for wanting to get and stay sober. It must be hard being so young and trying to stay sober when all your friends drink. Here's the deal though - it can be done. If you go to an AA meeting, you will meet others in your shoes. I went to one last night and was amazed at the number or young people there. What courage they have to tackle this! My ex boyfriend (still a good friend) is 45 and he has been sober since he was 20. He was in the prime of his partying and had a wake up call that he didn't want to wake up feeling like crap anymore and wasting his life away. He has not had a drink in 25 years. We just got off the phone and he said after rehab, he did two meetings a day for an entire year. That's how committed he was to his sobriety. It did mean meeting new friends as all the ones he'd known still partied. He has had a really good life as a result of his sobriety.
You can do this, you just need to want to bad enough and get support systems in place. Support is key. I think it's pretty much impossible to do on one's own.
Hang in there. You are doing great reaching out for help. Consider AA. The program saves lives.