M.,
My daughter was also older when taken off the bottle. She was born with a heart defect, so the doctors had me keep her on formula longer, and then once on whole milk continue with the bottle. I also experienced the same thing. Once given the green light that she didn't need the bottle, she would NOT drink milk from the cup. I was frustrated and worried, because she would drink so much from the bottle, and then to go to no milk at all.
Two things the doctor suggested to me were the Flinstone vitamins with added calcium, which she is still on. Also, Minute Maid Kids OJ has more calcium in it than whole milk. So, in the beginning that's what I did, she took the vitamins and drank the OJ, and for whatever reason after a while, she did start to drink milk. Although, she'll only drink it with a little chocolate in it, but the doctor said that's fine.
It's hard not to worry, but eventually I am sure she will start to take it. Good Luck!
B.