I wouldn't worry about it really. DD switched to a cup at 18 months and hasn't had bedtime milk for months now. I give her a drink of milk with her breakfast and her tea, she has milk on cereal, yoghurt in the day and cheese with some meals so she gets plenty. She doesn't need the bottle either, so it's a good thing she has dropped it by herself! Just offer milk as a drink in the day and dairy in foods and she will be fine!
Laura