Don't know where to start

My daughter is 16 and over the years I have often thought she shows signs of autism but never looked into anything official. Over the last 12 months (exams, starting college) she has become very unsettled. 

She is very emotionally up and down - could be normal teenage hormones - but they are often to extremes 

She has become more socially awkward - initially put down to COVID and low interactions for so long. She will not speak to people she doesn't know , won't answer the door ( will sit in tears if she is put in the situation) won't buy things in shops, often comes across rude to family members because she is very short with them when spoken to.

Is extremely anxious about illness and believes something is wrong with her all the time, a headache is a brain tumor ect

She does not like social situations, parties, meals out ect

Picky with food and textures, will only eat what she knows and not try new things. 

Will not wear certain materials because they 'feel funny'

I work in education and often see parents pushing for a diagnosis (even with children we do not see signs in)  so I guess I am just wondering what some opinions are? Am I looking for something not there to fix other issues or does it sound like she may be on the spectrum and if so what do I do and where do I start?

I've not even shared my thoughts with my daughter because I don't know how she will react?!