Help breastfeeding!!

I’m a new mom. My son is a week old tomorrow. Already had to bring in a bottle because his weight wasn’t were it should be.. I’m pumping so he gets my milk, but right now I’m only pumping about an ounce each time, and he can eat more then that in a feeding.. we have brought in formula to help with the difference. But I guess my question is, did anyone have this problem and was still about to breastfeed well? And what helped bring your supply up?