My almost two month old has still been drinking 2 ounces but recently she still acts hungry so I…

My almost two month old has still been drinking 2 ounces but recently she still acts hungry so I made 3 ounce bottles. Sometimes she will drink the entire thing and other times she won't. I don't like wasting Milk so how do I know when she actually is ready for more? Last night she had 2 ounce bottles but woke every hour hungry, is this a sign?