First question - Does she have tubes in her ears for the fluid? If not, why? I went thru ear problems with my first child and it was a nightmare and for whatever reason never did the tubes. With my son I did not hesitate. I think because I am older now and less worried about the surgery. He even went back and and had his adenoids out. The fluid in my sons ears was so bad that our ENT fit him in for the tubes one week before we left for a Florida Vacation. Anyway back to your question.
If its just that she doesn't like sippy cups maybe you can do something fun to transition to them. What we did was say that the Easter Bunny was coming and would bring her presents if she sacrificed her bottles. She did it. We got a huge basket, she put all the bottles in it and in the a.m. they were all gone, never to be seen again and the basket was full of all new cups and presents. She never asked for a bottle again. So you could do this, you could just tell her than the bottle fairy is coming tonight to take the bottles away. Even if she rebels, she won't starve, eventually she has to drink. Stick to your guns. I know its hard. I'm trying to get my son to sleep in his own bed and that is a battle in itself.
I know they have a new style sippie cup too that doesn't have the pronounced spout and is better for the kids as far as looking toward the future and speach etc.... It is almost like an adult coffee mug with lid but they work great.
Maybe try sippie cups with juice for a bit or even try warming the milk a bit, my son loves it that way.
Otherwise, get a second opinion from a different ENT. I didn't like the first office I went too. Too much like a production line. Small and personal is much better in my opinion.
Hope I didn't blab too much.