What’s the right amount of formula for 3 months

Asma

My baby is 3 months and I give her 4 oz every feeding which sometime she want every 2 hrs or less and cry every time after the feeding as she want more specially after longer sleep but she calms down after burping and need to giver her pacifier, I read some articles that the baby only needs 3 to 4 Oz from month 1 to 6, her Dr said to do what feels right to my baby and I don’t want to over feed her, how can I make sure that she gets enough, and how much should she gain weight monthly ? to know if am under feeding her 😔