How many feeding bottles should I buy?

Plan ko sana ( not sure what's the right term i'm new to this stuff hehe) ibreastfeed si baby and stash my milk. And when I'm at work the nanny will bottle feed my baby with my breastmilk. I already have 2 pcs 4 oz and 2 pcs 8 oz. Mag dadagdag pa sana ako ng 8oz but I read na yung mga babies na feed sa breastmilk, 4-5oz lang ang nacconsume every feeding. May mga mommies ba na nagpupump dito? Ilang oz na bottle gamit niyo? Nagagamit niyo din yung 8oz? How many feeding bottles do you have or nagagamit niyo? Educate me pls. I'm a new mom :)