Exclusively pumping

Hey mamas! I was hoping someone could offer me some advice. I am struggling with pumping! My little guy is almost 4 weeks eating 3oz every few hours but I can’t seem to pump more than 2 oz a session so I’ve been supplementing with formula since day 1. Last week I started breastfeeding supplements, drinking milk mamas tea and eating more oatmeal nothing seems to be helping. I even started power pumping this week. Does anyone have a similar experience? I’m starting to wonder if I should just formula feed all the way. It’s really bothering me that I can’t do this. Also, I think my period is restarting. Can that be the issue?