i have a similar thing with my 2 and a half week old, when i give him a bottle he will only take 2 oz, he physically wont take anymore, if you try and give him more he either spits it out or brings it straight back up, yet an hour and a half later he is screaming for more. i do give him another bottle when he wants it and he will take another 2 oz. i suggestd to my midwife that i may change his milk for the next step up intended for hungrier babies but she said that i shouldnt ,i cant remember what she said about it,, i have a really bad memory

but she was strongly against it. he does go 4-5 hours at night without waking for a feed so i dont really mind. if your boy will take more, i think you should give it to him as it may help him to last longer between feeds