My baby only 2 weeks old, and she already ate 3 onz formula, and it seems not enought, at night around 10pm - 2:00am she keep crying for food.. eg
10:30 had 3 onz then after 10 mins cry again for food.. we feed her with water 2 onz, she still cry for food and we have to feed her again at 12:30 am .. is it normal that she is always hungry every hour? should I add more onz to 4 onz...
Why not? My baby takes 5oz when he's 2 weeks old. The intake suddenly jumps from 3 to 4 then to 5 oz. Give another 0.5 to 1 oz when she seems to be crying for milk, and observe how much she can finish, and whether she can sleep better and longer. Then you should be able to know how much she should intake from then on.
I have the same experience. I read a book and it said that sometimes babies cry loudly to ask for more milk because they want to use up their excessive energy to have a better sleep and this usually happens at night (as crying and drinking milk are really exercise for babies). So, if your baby doesn't take too much more, just let him or her to drink. For my case, I usually give him extra 1 oz and he will sleep after taking it, sometimes he just drinks half of it and fall asleep.