How much is your 2 month old eating and how many hours apart?

My daughter was born on 2/18 at 35 weeks. She was in the NICU for 5 days to learn how to eat. She came home drinking 40cc approx  1 1/2oz every 3 hours. She is now drinking 4-5oz every 3-4 hours and still acts like she is hungry, but if she gets anymore she gags and spits up, then an hour later she is hungry again. So I will stop her at 4oz and sometimes she is satisfied and other times she is not. Anyone else experience this? I try to hold her off by a pacifier, but she spits it out and continues to cry. I don't know what to do. She is formula fed (Similac allimentum)