I have been exclusively pumping since 1 week after my baby was born. He is now 6 weeks old. Sometimes he will drink 3 ounces and other times he will drink 1 ounce. Is this okay?
Most grown humans do not eat the exact same amount for every meal and snack. Infants are no different. It is normal for a baby to want different amounts at different times. Some babies might take in the same amount at each feeding and stay on a schedule, but this is rare.
On average, breastfed infants take in between 24-35 ounces of breast milk every 24 hours. Newborns take in smaller amounts more frequently, but as they get older, they take in larger amounts less frequently. Even though you are exclusively pumping and bottle feeding, you can still feed your baby on demand.
The best way to help baby control his feeds is to pace feed him, which lets him decide how fast and how much he drinks. Your baby fusses for many reasons, not just hunger-- so only offer a bottle when your baby is showing hunger cues.
Here is some information on how to pace bottle feed your baby. When your baby is hungry he might lick his lips, turn his head, or suck on his hands. This is the best time to offer the bottle. Sit your baby partly upright and hold the bottle by his lips, but angled partially downward. When he starts to draw the bottle nipple into his mouth and suck, angle the bottle upward filling half of the nipple with milk. When he slows sucking or even stops sucking, angle the bottle downward again until sucking continues. This style of bottle feeding can seem like it takes a while, but is best for your milk supply and his digestion.
Paced feeding removes the risk of your baby eating too much too fast. This lessens overfeeding, gas, spitting up, and also helps you keep up with pumping amounts.
SOURCE: https://www.medela.us/breastfeeding/articles/how-much-breast-milk-does-a-baby-need
https://www.health.state.mn.us/docs/people/wic/localagency/wedupdate/moyr/2017/topic/1115feeding.pdf