I just started dd2 on bottles of EBM - I'm trying to do one feed per day to keep her in the habit

. DD1 never took a bottle, so I'm not sure what's a good amount to expect her to drink. I've been putting 3 oz in, and she takes about 2 but I'm not completely sure she stops there because she's had enough or for other reasons (gas, fussiness,etc.). Any thoughts? TIA!