I see this is a rather old question. How have you and your girl survived the past few years ?
There are bra’s and camis especially for sensory sensitive girls; https://bleuetgirl.com/pages/sensory-aware-apparel
Re periods I would go for the period briefs. You can even get them nowadays at BigW

Think You should seek professional help and there are also many suggestions on Autism websites. Do you have NDIS finding for your girl ? If not try to apply for it and if so make it part of your goals.

There is a fantastic book out by Tony Attwood, and he also has lists of books from other authors when you click on the publications tab on his website http://www.tonyattwood.com.au/
My son is autistic and gosh he was a Godsend. All the best

Good for you Miss Sammy. I wish you well. you are a great mum

I am seeing someone for me, and as they said every child is so different and her conditions can make things more complex but wont know til we there.. so I will just go with my gut and trust my heart that I can be there for her and do right when the time comes! its all I got. A few mums have told me of certain brands for underwear and pads that their daughter prefered more so that in itself is A HUGE HELP xxx

It is great to see you have professional help available for when the time comes but what about before hand? They might be able to help you explain to your daughter what to expect and what she might feel

Thank you Bella. I am doing just that.. Got my referral for a specialist who can help me and my daughter when the time comes. Think its more me so I can cope on a way my daughter will benieft Fromm thank you for the advice

I really think this might be a situation where you need to get professional advice.

Wishing you best of luck..change can be so difficult..

Thankyou BOTH for the great advice – I Will look into all your suggestions. Thankyou ever so much. means more than you could know =)

my sister has recently gone through something similar with my niece.
She started with crop tops instead of bras.
you will find a lot of great information on some of the autism websites

I really wish I could help, I do work with a few people who have children with autism and they attend specislists/therapies – if your daughter attends anything like this maybe the specialist/therapist could suggest something? I wish you luck