J.S.
I had the same problem with both my kids. As soon as they could drink from a sippy cup, I took the bottle away. But they had been so attached to the bottle, they didn't want the cup. It was so hard to do and several times I just about broke down and gave them the bottle back! There were some days I could swear they didn't drink a drop. I tried different kinds of sippy cups and that helped a little but eventually it just got easier for them and I was glad I didn't back down. It takes time, and when you're a concerned mother it seems to take even longer! Try whatever you can to get her interested in her cup...give her juice in them or try switching up the type of cup. Give her fruit more often so you feel like she's getting more "liquid" in her diet. Hang in there because it DOES get better! :) If you get overly concerned, don't hesitate to call that doctor.