Have you also thought of the idea that maybe she’s masking some of those symptoms around you? A lot of the language in your post seems judgmental, if just ignorant. It could be she’s willing and able to internalize those symptoms around you or other people in order to make her life easier - lots of us do it around family because a LOT of parents wind up coming out of the gate sounding like you, and it’s easier to just go “look I’m fine” rather than have to justify our diagnosis constantly.

Autism, especially what used to be considered “high functioning” autism like Asperger’s, isn’t always a “constant” feeling of these symptoms anymore than an average schizoaffective person or someone with BPD or someone with bipolar is constantly experiencing their own symptoms. You have good days, you have bad days, and you have triggers and sometimes you can nut up even on the bad days and go to work or school or whatever. Autistic people aren’t constantly Rainman-ing their way through life, or constantly reenacting Sheldon from Big Bang Theory or whatever your popular conception is.

You’re already saying “she’s mostly not off”, so why is it so hard to believe that she has this disorder, or that it’s hard to take the next step and say “huh, she says that the medicine really helps and makes it easier for her, so I’ll believe her on that.”. I understand wanting the best and worrying about things like chemical dependency, but her doctor should be - and almost certainly IS - monitoring for this at regular checkups.