Welcome to SR! This is a great place for support.
Many of us have been drinking to deal with social anxiety, myself included. It worked for a while, until it didn't anymore. With the amounts of alcohol you are consuming, I think it might be a good idea to reach out for medical help to detox.
You're saying that "a positive note" is that you're getting more outgoing. Well I was too, until I instead isolated myself competely and had to relearn how to interact socially. Maybe you also would like to talk to a councelor about your social anxiety and find some help to be able to go to school sober.
You are young and can get through this to lead a good and sober life! Stick around!