Dosage of Feeding

Hello! First time mum here. My LO who is currently 19 days seem to be hungry always. I am currently feeding her NAN fomula 60mls every 2hrs-3hrs (sometime she gets hungry 1.5hrs) once in a while, i do pump breastmilk and subtitute it w/ fomula milk w/ same amount. There were days that she is still hungry even after feeding 60mls! How much do u usually give your LO when they are still just days old?