First, you need to check with your pediatrician regarding how much formula she should be taking. If she's happy, alert, peeing and pooing on a regular basis, then she is most likely eating enough.
One way to determine how much a baby should eat is to feed them when they are hungry and to stop when they are full. The rule of thumb is to offer your baby 2. 5 ounces of formula per pound of body weight in a 24 hour period each day.
The recommended age for starting solids is six months), the general rule of thumb for formula amounts is 2. 5 - 2. 7 ounces (oz) per pound (lb) of body weight.
An eight month old baby should be getting two eight ounce bottles every day. All of their other nutrition should be coming from table food and milk in a sippy cup.
