A.F.
Hi Amy, my son was breastfed exclusively for the first 4-5 months then we introduced a bit of formula, but at that age he was taking about the amounts you describe. As long as your girl is not hungry, growing and urinating enough (so she's not dehydrated) I'd say you're fine! I can relate to the pressures you are facing and not knowing how much to give in bottles at day care when you are nursing. Trust yourself and it will all work out fine :)
A.