Hi,
My almost 7 week old dd takes about 5-5.5 oz every 3 hrs or so, but when she is full she won't take any more, she will play with it in her mouth and spit it out and gets fussy. I will burp her then offer more, sometimes she will take it, other times she won't. I just let her decide how much she needs. She isn't old enough to be impacted by how much she "should" have, she will take what she needs. It's a shame that society can't take a leaf out of the book of babies, they never worry about being to fat/thin etc...