How much formula 11 week old


We feed our 10 wk 5 day old 4 oz every 3 hours but sometimes he wants 5 oz and sometimes hungry before the 3 hours. Offered him 5 oz this morning and he spit up a lot. Just wondering how much formula everyone's baby is eating. I think he slept better last night with a few 5 oz bottles yesterday. I'm thinking he is needing 5 oz now!