My 2 mth old is fed. Lately she is eating poorly usually past 3 hrs during the day. what is normal?

She didn't have great BMs yesterday but today has had 2 large BMs one in which I had to bathe her. She seems like she is eating well but she will start to root or show signs of being hungry and will not eat well. She will latch on but will not eat. I have milk but she just pulls on and off. How long is normal for baby to eat during the day and how often for fed baby