The most obvious thing in your email is the fact that you are drinking everyday for the past 10 years — and are asking why you are depressed. Almost all of the things that you are mentioning, being scattered, underachieving, anxious, etc., are in some way tied to alcoholism or abuse. Why not deal directly with the core issue. Nothing, no form of therapy or medicine, is going to help if you don’t deal with the drinking. Alcohol is a central nervous system depressant. If you are taking it in everyday, you are not giving yourself a chance.
My strong recommendation is to use one of the most effective programs known to cope. Alcoholics Anonymous (AA) is available in your area. Go to a few open meeting and see what they have to offer. If you want to get a handle on being happy — start with untangling the thing that is holding you back the most.