My 18mth old still has 2 bottles of milk a day....

My 18mth old still has 2 bottles of milk a day. One before her nap and one before night time bedtime. I am not worried that she is actually having the milk as she doesn't use it to go to sleep etc, it just helps her to relax and is nice cuddle time. The thing that I am abit concerned about is that she is still drinking the milk from bottles. She drinks her juice and water from cups, straws etc, but she will only have her milk from the bottle. Is this normal or should I be pushing the issue for her to have her milk from a normal cup. Thanks for listening.