You can still enjoy a drink, just pump beforehand so you have milk already, and they actually have tests at most drug stores to
test alcohol level in your breast milk so you know when it's okay to feed again, though a small amount will not effect much in the first place. There are many ways around it, it just takes a little ahead of time planning. As far as sagging goes, most likely it'll be the same either way. That's just how it is unfortunately lol.