Dude if you cut the alcohol you'd easily cut a minute off your 10K. Try it for a month and see how it goes. The 2-3 a night hurts you b/c it disrupts your sleep but the blowout is what can really impact your ability to train. It also impacts your weight even if you were drinking vodka tonics that's still an extra 2000 to 2500 calories per week if you were drinking a microbrew you're talking 3000 to 4500 calories per week. These are by and far empty calories you aren't getting any protein or other nutritional benefit from you alcohol consumption.
On a personal note I usually drink a few days a week with perhaps one heavy day on Friday or Saturday and can run a 5K in 18:50 to 19:05 without too much trouble and in fact I've had time times as low as 18:45 after heavy nights of drinking but I feel it and I just can't get into my extra gear and there's been a few times I just hit a wall the last mile. I feel it way more when I run a 10K it's hard to get sub 40 after a big night of drinking.
If I get more serious either b/c I have a upcoming race or just want to focus more on my training, I'll stop drinking and within a couple of weeks I can get down to a sub 18 minute 5K pace with no difference in MPW just the stopping drinking improves my 5K time by about a minute, mainly b/c I have more stamina and not bonk.
I don't put much thought into my drinking b/c I'm not that fast but If were able to run a 31:50 10K I'd definitely be laying off the sauce to see how much faster I could go. Based on my experience I think you were leaving a minute plus on the table with your 10K and 30 seconds or more on the 5K.