Hi J.,
My daughter has Sensory Processing Disorder and is on the high-functioning end of the Autism Spectrum. While she's doing very well now (almost 13, in 7th grade, plays tenor sax in band, takes jazz dance, made the Dean's Honor Roll), we had to go through many years of ploughing through the thickness all by ourselves.
Our daughter didn't actually speak either when she was little. When she was 3 years old, I took her to a school evaluation and had the school district evaluate her; she had a severe speech impediment and took speech through the school district from age 3 until 6th grade. When she was in daycare, they actually taught her a few hand signs/American sign language so that they could communicate with her. That helped us as well. I was the only one who could communicate at all with her, because I was the only one who could understand her.
Is your daughter aware enough that you can teach her some signs/words so you can work on communicating that way with her? I don't know how bad her autism is; does she understand words/commands/is she able to follow directions? Would a talking board help her communicate? I'm just throwing some ideas out there. Is the school district doing anything with her in terms of speech to try to help with her speaking?
My daughter has a boy in her class who has severe autism. He was in speech class with her and in Early Childhood with her. The school district my daughter goes to happens to be THE BEST one around this area we live; in fact, this boy's parents have been driving him 20-30 miles one way to our school since he was three years old so that he can partake in their Special Education class. From severe autism and no expressions, no talking, no eye contact, today he makes eye contact, he has expressions and laughs, and he can talk. His dad has been teaching him about what's mine, how to act around others, how to defend/take care of himself (he'll take his son's baseball cap and put it on his head, and his son will take it back again and say, Mine. That sort of thing.).
I guess you don't give us enough information to really give you a solid answer. My question would be, how severe is your daughter and what has been done up to now to help her learn how to speak?