Hi,
First, I'd let her know that she doesn't need to make any challenging decisions while she's ill. Life is long and life is very flexible. There's no rule that says you must do A levels within two years or go straight to uni. All sorts of very happy and successful people make their progress in their own good time.
the most important thing, by far, is for her to get well from depression and then, when she feels ready, if she wants to, look into any ASD assessments and support she might want.
Wrt getting better, you can best support her by recognising how profoundly physical the disease is. It's a bloody nightmare: the depth of exhaustion, the mud-for-brains, the incredible loss of motivation to bathe, eat, move, communicate in any way.
Help her towards a gentle routine of physical self care: a daily shower or bath; clean clothes and bedding. A daily walk in the fresh air is essential. Some form of physical exercise daily. Nutritious foods.
Tell her that if and when she feels ready to discuss or act on plnas for her future, you'll help her as much as she wants.
That's all you can do. Until she's well, it would be unfair to try and push any decision on her.
DS2 has ASD. We've been lucky. The school was well set up to support him and really has done. When time comes to look at unis, I will make it a priority to check what active support systems are in place for ASD students and make sure he applies to unis that will help him as much as the school has.