The percentage of alcohol in your blood is the same as the percentage in your milk. For milk to be defined as an alcoholic beverage you would have to be dead. The biggest issue is being coherent enough to care for your baby.

Orange juice has an alcohol content of 0.1% and is considered a non alcoholic beverage. A non alcoholic beverage is anything up to 0.5%. So for breast milk to be alcoholic your BAC would have to be 0.5, which is 10 times the legal limit for driving and is also lethal.

So have a few drinks, and make sure you are coherent and you should not have any problems. Go, Drink and be merry.