I'm glad you posted, welcome. Your story suggests an addiction issue, as you know, and the first thing to do is to stop drinking. That can be so hard, but you will find so much support here. You're lucky in a way that you've recognised your problem so young. If I had recognised an alcohol problem when I was 22, the next six years of my life might have been salvagable.
I too am / was a writer, and after a while my alcohol problems completely robbed me of my ability to write and think properly. I wrote a PhD while I was a severe binge drinker, and afterwards I was intellectually wiped out and broken down. A year later, I have not recovered and still have no concentration span at all. You obviously value your high IQ, but alcohol is very damaging to the brain and to thought processes. If you keep going you will notice your thoughts slowing down a bit; making connections between things (essential for artists) takes longer. Now that I have quit, I'm looking forward to being able to write again. I hope you can get through this, and come on here whenever you need to talk.