My DD has Aspergers and can take things literally, at times. She also has anxiety and hates other people's blood.
I bought her a number of books, including:
Secret Girls Business
Puberty Girl
and can't remember the third informational book.
Also bought 'Are you there God', it's me Margaret. My DD wasn't a fictional reader, but did take this book in, and still refers to it years later. I chose to get it for her, as I couldn't see her discussing it with other girls, so at least she could kind of experience it from the point of a young girl via the book.
I went into the bookshops with her, looked at what was available, and chose the ones that I thought would match her comprehensive/sense of humour level. I gave them to her to read and told her she could ask me questions any time she wanted. She learns better by reading as opposed to listening.

They have been an invaluable asset, as my DD has been able to read them any time she had questions. She also then felt comfortable to discuss things with me, I was actually quite shocked with how she handled it all - and I attribute that to the books.
One of the important issues you might come across, is her ability to be discreet about it all - so one of the books I got does cover this - about how to dispose of a pad etc.
Some kids with Aspergers can have issues with hygiene (eg daily baths and regular hair washes, using deodorant etc ) so there is a good book called "Personal Hygiene? What's That Got to Do With Me?" if it does become an issue.
Check your school library if they have any books. I know my school bought some a while ago, but no longer advertise them - but parents are/were allowed to come in and borrow them from the school library if they were needed.
Also check your local library.
I think having your own copy of books is a great resource for kids, so they can look at any time they want, but it's a good idea to check the books out before you buy them in case they won't appeal to your child.