Lactating moms will have to deal with these at some point, so I’ll save you some frantic researching and let you know the deal:
If you screw up your supply and it starts to get low - pump/nurse more often and pump longer than normal. Removal of milk signals your body to make more milk.
If your kid has a favorite boob and one gets bigger than the other - try to “ignore” that side and use the other side. Your ignored boob will get bigger and uncomfortable, so nurse long enough to take off the edge…then throw baby back on the other boob. That D cup/C cup life is no bueno.