Emmy, many of us can relate to this. If what you described is accurate, your husband is not physically addicted to alcohol; however, it appears he cannot control his drinking when he does drink. My drinking patterns were very similar to your husband's. I went weeks without even the thought of drinking, but when I did drink I could not control myself. Two or three beers were never enough. I would drink until I was stone drunk.
I'm afraid your husband's quest to be a normal drinker is in vain. IMO, he will never again be a normal drinker, and the only sensible option is to quit for good. He won't like that idea--at first, but he should reflect very carefully on what happens once he takes that first drink. Ask him if he has ever controlled his drinking over the last three years or so? If he has, how many times? Then ask him how many times he lost control once he started.