Yeah, nursing and pooping is basically what newborns do. Assuming she's getting some naps in there during the day, she's pretty much on track. Newborns nurse every 2-3 hours, but that's from the beginning of a feed to the beginning of a feed, not from the end of one feed to the beginning of the next. And sucking is really comforting for new babies, so if your boobs need a break, try a paci. That said, all that sucking is what will stimulate your supply. I wouldn't supplement at this point--your baby is growing and you don't need to be worrying about pumping.