Breastfed babies
Breastmilk is complete and therefore normally covers the baby's feeding needs. But it is important, during a breastfeed, that the baby receives both the first thinner milk, satisfying thirst, and then the final fatter milk (hind milk), which makes the baby feel full.
Some babies will be satisfied by feeding from one breast only, while others will need to feed from both.
As the baby grows, there will be days when the baby's need for food increases significantly. The baby will self-regulate the amount of the milk by eating more frequently during this period. This is called demand feeding. The more the baby demands/feeds at the breast, the more milk is produced.
During a mothers normal menstrual period, regardless of bleeding or not, hormone changes may affect the breast-milk flavour. The baby will adjust to the new flavour but may briefly reject to take the breast.
Bottlefed babies
The amount of milk, for babies receiving infant formula, is about 1/6 of the baby's body weight per day, spred over 6-8 meals per day.
It is normal that the amount ml per feed can vary through the day, and it is a good idea to add 10-15 ml more to the bottle, than the amount you expect your baby to eat. As the baby grows, it will require bigger feeds.
Varius infant formula preparations are available and you should consult with your family doctor/health care professional, if you are uncertain as to which product is best for your baby.