Michelle,
I have been thinking about both you and your daughter and knew your trip was fast approaching. I hope you have a magical time. Please let us know how it went.
My only last minute advice would be to pack a pocket sized package of Kleenex. When I took my DD with autism for her first trip, I had no idea how she would do. The clinic director where she has therapy even told me that not one of the families she worked with took a vacation where they didn't come back and tell her they wanted to come home early. Being hard-headed, I didn't listen and I am soooooooo glad. My DD had the time of her life.
She enjoyed those rides more than I ever imagined she would and there were moments where I would just fill up with tears watching her. Words cannot describe my feelings at her first character interaction (Pluto). She grabbed him around the mouth/nose and squeezed so tight. When we saw Mickey, she kissed him on the nose!!! I was crying like a baby. I'm crying now just thinking about it. It is, for us, truly the happiest and most magical place on earth.
Everyone on this board knows the heartache and disappointment that goes along with having a special child. I hope the magic of WDW fills your DD and you experience the joy there that we have.