Sorry, Newbie, that you are going through all of this. Big hugs to you.
What you are describing sounds like progression of the disease. My ex, who I didn't know for some time was an alcoholic, gained 50 lbs. (all around the middle) from the start of the time we were dating. He also had a lot of trouble with sleep. He would snore loudly and would never sleep more than a couple of hours at a time. It's horrible to watch, but even more sad when you realize why it's happening.
I would read "under the influence" and "getting them sober." They will give you an understanding of the progression of disease. It will also give you ways to cope. I think your therapist is right in that you should not nag him about the drinking. Let him know it upsets you, but don't make any threats you are not willing to follow through with.
If he's going without alcohol for a couple of days he could start to detox. I wouldn't be shocked to learn later that he his some alcohol somewhere in a suitcase or a coat pocket. I've read this happens A LOT.
Take care of you : )