baby keeps squirming while nursing?

Sometimes when my baby nurses she starts squirming, kicking, stretching, making all kinds of loud weird noises(grunting, moans, etc), and her eyes will be closed, but no real whining or crying. I try taking her off the breast and burping her(sometimes she does or doesnt) but then she starts again when she latches back on. If I dont let her latch back on she cries, of course.

I cant tell when Im having a let-down and have no idea if its too fast or slow. 🤷‍♀️My baby is 3weeks old and when I pump Im getting 4oz total.

Im not sure if something is wrong or maybe its just how she nurses?

Any advice?