A.M.
you do start to drink less at that age. my daughter didnt have any drink with her meals, but had the bottles in between as her "snack". i would say she drank 1 mid morning, 1 mid afternoon, 1 after dinner and 1 before bed. 6 ounces per bottle. i disagree with another poster, the main nutrition should still be coming from the formula which has complete nutrition. unless you are giving her complete meals using the pyramid system or similar to ensure proper nutrition, the chances of getting her complete proper nutrition from "solids" is pretty low for the average person to accomplish. solids do replace the formula as her stomach can only eat so much, but you just need to make sure you dont continue to feed her the solids disregarding the formula.
try to get her to drink 20-24 ounces. give the bottles in between meals. if you also feed some sort of snack in between meals, do so after the bottle. you can give water to hydrate but only do so after you know she has gotten the proper amount of formula.
if she doesnt do 4, skip the dinner one and only do the before bed. just dont give a snack before she drinks or else you would have filled up her belly. good luck