I weaned my first son at 17 months, you'll be able to do it.
One thing that may be complicating it is your trying to have her do 2 things at once - 1) wean 2) learn to fall asleep by herself. Try picking 1 of the 2 to do first. For me I did let him cry at around 15 months while we were still nursing so I could nurse him when he woke up. If your set on weaning first can you rock her or drive her to sleep.