I had this issue when BFing DDs too, but I don't remember ever doing anything to help it. when AF hits, my supply seems to drop off a bit. Right now I have what seems to be the start of AF and when I pumped a little while ago, I only got 2 oz when I usually get about 5. Obviously DS isn't going to be satisfied with that when he is used to getting 5 oz. what can I do to try and bring my supply up during AF? And will trying to increase it right now give me an oversupply once AF is gone and things return to normal? In the past, my supply always seemed to bounce back once AF was gone.
Some women find adding a calcium/magnesium supplement helps. Can't hurt, anyway. Your supply should rebound post-period. You don't need to worry about an oversupply. All you can do is pump/nurse more often and wait.