You're in an almost identical situation to where I was about one month ago.
I am also mid 30s, I also had about 4 and a half months of sobriety under my belt and I was feeling fantastic. However I had a feeling that I'd be able to moderate drinking, so felt I should go back and give it a try. I then let a social situation develop where I was kind of under pressure to drink, so I did. Well, it's just not worth it. The experiment failed. The hangovers are just as bad, or worse, than they were before I quit. It hasn't got any easier to moderate it. I ended up drinking on two subsequent weekends following my initial relapse. Nothing terrible happened the 3 times I drank in September. However what I was reminded of was, that I am powerless over alcohol. Once I have one drink or sip, I have to drink until I get very drunk, as otherwise what is the point? Then I usually just pass out. I then wake up the next day feeling anxious, depressed and craving another drink. This is no way to live, and I am setting myself up for being unable to stop drinking, and ending up on a binge. Then **** gets really bad. Once you go back there, drinking has a nasty way of working itself back into your daily thinking and that isn't a nice place to be.
Remember, no one ends up on here, or in AA by accident. People without drink problems don't end up on here or in AA. The fact we do, is because our life has become unmanageable with alcohol. We can never go back. Don't think you can control it, you can't. We are powerless over Alcohol.