Have you tried feeding your baby any infant cereals and infant fruits and veggies. Sometimes the formula alone does not make them happy. I run a child care and one infant is happier when she is eating food from a spoon vs her bottle. My own daughter did not care for the spoon at 1st so I had to add cereal &/or fruit or veggies to her bottles of formula. I also learned a lot on the food program for my child care, such as what and how much to feed children at different ages and stages.
According to the meal patterns guides lines of the food program I participate with...
Infants from 0 to 3 months
Breakfast:4 to 6 fl oz of Breast milk or formula
Lunch/Supper:4 to 6 fl oz of Breast milk or formula
Snack:4 to 6 fl oz of Breast milk or formula
Infants from 4-7 months
Breakfast: 4 to 8 fl oz oz breast milk or formula.
0 to 3 tablespoons of infant cereal.
Lunch/Supper: 4 to 8 fl oz of breast milk or formula, 0 to 3 Tbsp infant cereal, 0 to 3 tbsp fruit and/or veggies.
Snack 4 to 6 fl oz breast milk or formula.
Infants from 8-11 months
Breakfast: 6 to 8 fl oz oz breast milk or formula.
2 to 4 tablespoons of infant cereal.
1 to 4 Tbsp fruit and/or veggie
Lunch/Supper: 6 to 8 fl oz of breast milk or formula
2 to 4 Tbsp infant cereal and/or 1 to 4 tbsp meat, fish, poultry, egg yolk, cooked dry beans or peas; or 1/2 or 2 oz cheese or 1 to 4 Tbsp cottage cheese; cheese food, or cheese spread; and
1 to 4 Tbsp fruit and or veggies.
Snack: 2 to 4 fl oz breast milk or formula or fruit juice
0 to 1/2 slice bread or 0 to 2 crackers
I hope this might help