I express milk and I also give ready to feed formula. My baby boy drinks different amounts every time. But roughly 90ml per feed. Once I open a bottle of formula, I keep it in the fridge for up to 24 hours so this way it doesn’t get wasted x
I pour 120ml if he’s due a full feed. he rarely wants more than that . If he wants more I can then add more.
If your baby is feeding every 2 hours or less then yeh 90ml or less could be fine
ours has 3 bottles a day and breast feed in between/ over night. we make 6oz as the box says for 4mnths but they normally only drink 4oz, sometimes less sometimes more
If she's mostly BF, the amounts are 1-1.5oz per hour so that would fit. BM adapts to babies needs so you don't need to change the amount, formula you need to up the volume as they get older. If she's predominantly BF at the moment then I wouldn't worry about trying to get her to drink larger amounts of formula x