Because that's how she thinks it is supposed to be done. She is not a mind reader, tell her how you would like it done. Nicely. Knowing how is not automatic, it has to be learned. How good are you at...
I bottle fed all four of my children, so I'll try to help as much as possible:
Newborns generally take in 1-2 ounces per feeding, moving up to 2 oz, 4 oz, and eventually 8 oz as they grow...