Too much food ?

I know they say a sign of you baby over eating is spitting up after eating.... Buy if I try to give my baby anything less than 6 oz he cry’s for more. I’ve tried stopping less than 6 oz and waiting it out a bit. I burp him get the air bubbles out try to sing to him yet nothing soothes him except giving him the full six ounces. What do I do ?? Do I just continue to give him six ounces or what😕(I checked with my pediatrician and she said it’s because he’s over eating not reflux) also he spits up quite a bit...