My baby is 3weeks old now. How much formula milk is enough for her? She is drinking 80-90ml formula milk every 2-3hrs, is it too much for her?

Eh, actually its 150ml x (body weight in kg) - this will be the approx amount of fm that baby takes in a 24 hr period. F u giving bm or latching then this figure needs to be adjusted. There is a growth spout about 2-3 weeks old and at 4-6 weeks old - during such time, baby may drink and sleep in an unusually pattern - some babies will drink more, some will sleep more. Just make sure that when baby cries, its not because of diaper or colic or wind in stomach. Also don't force feed baby - then all is good