how do I know when it's time to increase my LO's feed amount? currently he's 16wks, drinking 120ml EBM/FM 7-8times a a day.. but my mil says that he isn't full coz he isn't sleeping..

A 4-month-old weighing about 6kg needs about 28-32 oz of milk which is about 830-860ml of milk. From your descriptions, baby seems to be having enough milk. If baby isn't full, he will definitely let you know by crying. I don't think sleeping immediately after milk has any bearing on whether baby is full. Perhaps he's just not tired yet?