Breastfeeding, alcohol, pumping.

So I haven't had alcohol since thanksgiving and I want to have my first drinks on my birthday which is at the end of the month (Oct). My baby will be 2mo and I'm breastfeeding. I give him a couple bottles of pumped milk at night when he's still hungry.

So if I have a night out on my birthday while my son gets pumped milk, how do I go about pumping so my supply won't tank? I'm not very comfortable with skipping for too long because I feel like I'm producing barely just enough. Tips please.