I bottlefeed on demand, at first becauseI was trying to keep it as close as possible to BFing & then when it was clear we wouldn't get back there I just kept doing it.

DD2 has never had the 'right ' amount for her age, she's always mucked around with how much she has & how often but her gains have been good... I just offered it to her whenever she grizzled, or it had been a while between feeds. You soon work out when they want it & when they don't, it's pretty hard to feed a baby who's not interested
ETA - posted at the same time - I used to put formula bottles back in the fridge, not for ages but just a bit (although you're not supposed to). Pie's EBM I just leave at room temp until she's had a decent drink. The other thing you could try is smaller bottles, to avoid wastage.
she diod loads of snack feeding, sounds like your boy might be the same.