Growing pains or something else?

Baby girl is 3 weeks old and has been so fussy and screaming bloody murder. She's eating a lot of food. My doctor told me to keep feeding her if she's rooting or still drinking. She can go from 60 to 100ml in one feeding. I try and top off with breastfeeding (not producing a lot so supplementing) and trying to pump when she's not screaming at me. She's roughly getting 500ml a day which I guess is roughly 17-18oz? Is this just a growth spurt? She's peeing and pooping normally and sleeping lots.... just super crazy fussy especially with food or wanting to be held by me. Losing a lot of sleep.