Not enough milk. Remember this is her food, not a drink. If she is getting cereal at all, feed it after a milk feeding and really only a tablespoon of cereal
Guidelines for bottle feeding:
The American Academy of Pediatrics (AAP), in the book Your Baby's First Year, says, "most babies are satisfied with 3 to 4 ounces per feeding during the first month, and increase that amount by 1 ounce per month until reaching 8 ounces." For a 2 month old, that means that your baby will probably be drinking about 4 to 5 ounces of baby formula at a time.
Some babies never reach 8 ounces though, topping out at 5 to 6 ounces at a feeding.
The AAP provides another guideline about baby formula, suggesting that "on average, your baby should take in about 2 1/2 ounces of formula a day for every pound of body weight." So for an average 2-month-old boy who weighs 12 pounds, that would be about 30 ounces a day.
Keep in mind that the average baby drinks:
•4 to 6 bottles of formula until they are about 6 months old
•3 to 5 bottles of formula between 7 and 9 months of age
•3 to 4 bottles of formula between 10 and 12 months of age
•3 to 4 bottles of whole milk or a toddler formula once they are 12 months old