Your infant's body knows when and how much to eat and drink even if it does not look like enough to you. If your baby is growing as s/he should you only need to feed your child when they signal with smacking lips, tongue out or fussing. If you are breast feeding and have a good enough supply (dripping is a good sign) you might be able to hear you infant swallowing and see satisfaction after a few minutes telling you s/he is full. Some babies will drink from a bottle until they vomit if you do not stop them. Babies who are choking or gasping a lot when drinking should be checked by the doctor. If your baby has good head control and seems hungry sooner than you expect it is time for 'solids' such as baby oatmeal. But spitting out food or gagging some is normal as they learn to eat. They usually get used to eating foods after a couple of weeks