Welcome to SR Collegegirl!
Functional alcoholic here too! I started drinking at 14 and had older brothers to get my booze and would often spend most week nights hanging with them drinking. I should've definitely been on here during university. You are very insightful and fortunate to realize this so young! I finished university, held down jobs, and travelled (living and working) all over the world, thinking I was just having fun with my drinking.
Well, at 36 I started realizing I had a drinking problem. You are sooo lucky to realize it so young. It feels like I have not made the most of so many years worth of opportunities because of my drinking. You still have so many opportunities ahead of you! You won't have to miss out on them b/c you are drinking so much.
IMHO, You are fortunate to be in university right now, because as mentioned above, you have LOTS of resources available. You have meetings and easy access to meeting others your age who don't drink and are going through something similar to you.
As far as the bachelorette party......yikes! I relapsed when I thought I could go to a BonVoyage party and stay sober (after 9 days sobriety). I had to avoid all situations with alcohol for a while at first. The only options for entertainment at first were coffee, movies, lunch, breakfast, walking around the city/parks, or shopping. In the evenings, I just said I was tired, had a headache, and eventually "I'm not drinking because I need to lose weight." That's where I am now.
My advice would be...... avoid the bachelorette party.
Best Wishes!