Advice please!

Hi! So I was exclusively breastfeeding for about the first week and a half. With my baby being pretty big (10 lbs at the time), I wasn’t sure how much he was getting and he always seemed hungry. I started exclusively pumping and it was working out, but now my milk isn’t as much as it was and I’m supplementing Enfamil Neuro Pro Sensitive maybe 2-3 times a day and he’s super gassy and fussy. Should I try go back to the breast? Or maybe try another formula?? Any advice welcome, thank you!