Hi Belle! You seem very insightful, so to be honest I'm surprised you're struggling so much with this; I suppose that pesky love thing :-)
First of all, 4-6 liquor drinks/day is absolutely an alcoholic as far as I'm concerned. That is a dangerous level of alcohol to maintain, and if he's able to be functional and keep down a good job, he's obviously been an alcoholic for quite some time and built up a serious tolerance. Digestive issues and weight gain aren't unique to alcoholism, of course, but they certainly are consequences of heavy alcohol intake. The neediness as well is a red flag, as you noted. The need for validation after feeling guilty due to drinking is very real and can be soo taxing on the partner. Has he ever gotten sloppy around you? Ever had to help him do normal things because he was too drunk/hungover?
It doesn't sound to me like you're ready to make a clean break... I would approach it this way: propose a booze-free weekend and see how he reacts. Before my alcoholism reared its ugly head, I'd been with a guy who always had alcohol ready for our dates, and i finally asked if he needed booze to enjoy my company. That's a fair question. I think that would be a subtle way to gauge if he recognizes it as a problem, because he very well may think everyone does that and it's normal. Now, this is of course not a perfect plan; he could easily pull off a weekend or whatever without alcohol just to please you. But it would open up the floor for a conversation without being too accusatory... maybe? Just a thought!!
Btw, do you drink? If you don't, I don't know how you can stand that!!!