I think everyone has made some very valid points. The title to your OP was "Alcohol is my downfall". Maybe it's the type of alcohol?
I had a very similar issue with beer - I didn't necessarily crave it on a daily basis but on the weekends I would pick up a 6 pack and would tell myself I would only have one or two but, before I knew it, the whole 6 pack would be gone in a just a couple of hours (and if a 12 pack was on sale so I got that instead - guess what? Yep, gone too). I knew it was not only getting in the way of my goal for better health but was a classic symptom of an addiction. Just cutting off drinking all together wasn't something I was ready to deal with since I'm in a town where there are so many business occasions that involve cocktail parties - if you don't have at least one, you get pegged as a recovering alcoholic who might fall off the wagon any minute and blow major deals
What I discovered is that having something other than beer - particularly something that I don't really care for, like scotch

- made it really easy to sip slowly (rather than swig wich I did with the beer). I also made a hard and fast rule that for every "adult beverage" I consume, I have to drink at least 8 oz of water before I can have another. For some reason, this switch to a different type of alcohol has made it really easy for me to stop after one or two.
I also think that those of us who have been struggling with our weight for eons have fallen into the habit of using alcohol to kind of soften our disappointment in ourselves and make ourselves feel more like we fit in with "normal" people. I know when I was *buzzed* I didn't feel nearly as fat

Quite honestly, I am probably still using alcohol as a crutch of sorts but now it's evolved into just carrying around that glass of scotch on the rocks like a security blanket and I don't actually have to drink it
You could try switching to something else for your evening cocktail and see if you are able to have one glass and stop. If you still have to keep going until you "feel the high", you may have to step back and think hard about whether the high or your health is more important to you
