It isn't how much you drink (to an extent I guess) or how often. It's how your body handles it. I used to tell myself all the time that I shouldn't worry about possibly having a problem because I only drank on weekends. "I out drink every guy I know, but I only drink on weekends so that doesn't matter." "I black out and end up puking every time I drink, but I only drink on weekends so it isn't a big deal." "I get this horrible pain in my stomach after I drink, but it's only on weekends so it's nothing to worry about." The list could go on and on. It doesn't matter, I AM an alcoholic. Once I finally came to that conclusion I figured out what to do. I had already been seeing a counselor on campus at my university so I brought it up and then started seeing a counselor who specifically concentrated on drug abuse. Talking to both of them every week has been enough to help me out. I tried going to an AA meeting and ended up getting into a car accident on my way there (no I wasn't drunk). I haven't tried since but I've told myself that if things get difficult again I'll have to go no matter how scared I am.
I know exactly why I drink. But even knowing that doesn't matter as much as I thought it would. I just need to stay away from alcohol, period.
My suggestion is to get into some sort of support group, whether that be AA, Smart (I think it's called), or any other group out there. I can't remember the names of the others at the moment. You NEED support, it's impossible to do something this difficult completely on your own.
One last suggestion is that if you're worried about withdrawals to go see a doctor that can help you with that so you can do it safely.
I hope at least some of my long post ends up being helpful.