i demand fed my DS. he used to feed every 3 - 3.5 hrs. which brand of formula are you useing? i know when i changed DS from BF to FF i was useing Karicare as the LC i saw said its consistency was closer to BM. the tin as tril said is a guide. if your little man is hungry offer him some more. when you cuddle your little man after a feed (and is unsettled) have you found him nuzzleing into your breast? i found that was a sign my DS wanted some more. it may also be getting used to the formula as well.