Formula shamed

My baby boy is 3 w 3 d and he was exclusively breast fed until I started stressing out; losing sleep ; and just worrying about his overall health and thinking that he’s not getting enough . He weighed 7 pounds 9.5 ounces at birth but since then his doctors have made me come in every 3-4 days to check his weight. They’ve said he’s not gaining enough that he’s still underweight so that’s why I started supplementing only at night . The doctors have really made me feel bad about that. It’s extremely hard to just breastfeed even when pumping , sometimes I only make a few ounces and with the lactation cookies and teas it doesn’t really seem to be helping . I just want to make sure my baby is a healthy weight and that’s the main reason I’ve decided to do both formula and breast. Any stories similar or advice is welcome !! 😊