I think SD has level 1 autism ( Aspergers ) as she cannot deal with anything new , huge social anxiety , hates textures and noises. BUT its hard to tell what is normal teenage behaviour and what isn't.
I think you may very well be right here. The bright light aversion can be a sign and certainly made me think this could be the case.
You're on really tricky ground here, as any diagnosis obviously takes time and medical professionals and this is extra hard when you're not in the same house.
Two questions:
1. have you discussed this possibility with your partner?
2. is there any of this is the rest of the family?
I have a good friend who went through something similar, his words when we discussed this were "I'd be really surprised, we have no history of this in the family."
My reply was "you work in data analysis for a hedge fund, your wife is a tax accountant I think that might be a leading indicator."
I'm being slightly flippant, and he is a good friend, but sometimes it's hard to see the wood for the trees.
My main advice, get professional help asap so you know what you're dealing with.
Good luck.