Hi W.!
I have two on the spectrum. Sleep is an issue for us too, and for most kids with this issue. We have had the most luck with medical care from psychiatrists, we see one who is very avalaibable, if we have an issue, we can usually get in that day. This has been a God send. Our youngest was nonverbal until she really started sleeping. She was put on clondine for sleep at age 3, and her speech started to take off once she did not wake every 45 minutes to check on where I was. She still would rather sleep on the couch than in her bed, and she is now 11. I have a friend who even got rid of her autistic childs bed because he never slept in it, he sleeps on the couch. So, I guess what I am saying is get some really good medical care because this is part of the issue, and try other things if one prescription did not work, there are others that my help. That, and if sleeping on the couch works, it may just be worth it to go with it. You do what you have to do, and sometimes (though it may not be how you thought it would be) you live with life the way it works best.
I feel for you. Sleeping will help you deal with her better too. I have so been there, but from where I sit, it does get better with age.
One suggestion, we have locks on our doors that she cannot undo. It is a saftey issue, because she could leave the house in the middle of the night. We use the push bar, really high and out of her reach. Another solution is an alarm.
I hope you get some rest, and I hope she does too. You will be very happy with her progress once she sleeps more too!
M.