Good for figuring it out! I'd say it's going to be trial and error, trying to figure out how much warmth and weight she wants, and/or what texture. My ASD daughter can't stand to be too hot, and also got very upset if the cover wasn't smooth and flat. A loose nightgown and a light sheet patted on top of her in winter, no sheet in summer worked best. She also slept with us for years, which is how we got some sleep... sometimes I regret transitioning her to her own bed, because it has taken her a lot longer ever since. I'm just saying that because if I were you I wouldn't worry about sharing a room or a bed with your daughter if that works. She is still young and, being on the spectrum, may still be in a co-sleeping phase of development.
J.