My story is a lot like yours. Going out and getting drunk w/ friends was the social norm. But no one knew I was putting away a handle of vodka by myself every 2 to3 days alone. We quit being "functional" alcholics when alcohol consumes us more than we consume it. We become obsessed with thoughts of the drink and thinking of how great it will feel to just get drunk, listen to music, play vid games/ surf the net, etc. But its not that great. Its not functional. You are destroying yourself all alone and its not okay to do so. Quit now before your liver quits on you...and it will quit on you if you keep going. I offer you any support you need. You've made it this far. don't go back. Keep staying sober and for now, thats enough.