I'm at my lowest point

Right now, I'm drinking one 950ml vodka bottle everyday at night, I'm 1,80m and 90kg and alcohol is the only thing that can make me do my everyday tasks, like work and college. I know that this is bad, I already do therapy and go to a psychiatrist, take 4 depression medications every day, but I still don't know why I have the urge to drink every single day, I tried to stop many times, but 1 slip and it's all gone. Maybe this is not the sub to post this, but I want suggestions on what can I do about it, not the usual stuff since I tried most of it