This is my 15 YO SD.
Mum & dad will not entertain or discuss the idea and the ‘challenges’ are getting more visible.
I would urge you to speak to dad in a non confrontational way to get the kid assessed.
My my case, these are the things I’ve observed (which mum & dad put down to being an introvert and fussy eater):
I have known her for over 7 years and not once has she had a conversation with me. This also goes for friends of ours etc. She only gives one word answers to dad.
She sits in silence or gives yes, no, don’t know answers. It’s painful to watch.
Doesn’t stick at anything and also has low concentration levels. As an example - at 15 can’t strip her own bed despite being shown numerous times or had it explained.
Has absolutely no interests and has no passion for anything. Watches TV or a phone screen. Does no exercise and has to be dragged out.
Prefers to be alone. Sits next to us on the sofa with head phones in. When asked to take them out & join in will just sit in silence.
Dinner time is a struggle. Is the fussiest eater - will only eat bland oven food. Won’t try anything new or there is a melt down.
Can’t get public transport on her own. Isn’t interested in getting pocket money. Has no interest in gaining any life skills. Doesn’t want to learn to cook. I would say she’s at a 12 YO level of maturity.
This has caused so many arguments between my OH & I. It’s not getting any better.
An assessment won’t do any harm. Good luck.