My 3 week old all day has been on and off nursing. And maybe sleeping for an hour til waking up and…

My 3 week old all day has been on and off nursing. And maybe sleeping for an hour til waking up and wanting more. She goes on and then she’ll latch off and start crying and squirming around. Is she not getting enough milk? Is it coming out to fast? Sucking just to suck? Ugh, I’m exhausted 🙄