Debra, I'm sorry you are dealing with so much. Don't forget how resilient children are!
All I have to compare this to is my situation. I knew I had problems while growing up but ignored them or simply adjusted my physical activities. I have AChR modulating antibodies. I think it has to be a subset of MG. They should keep retesting her antibodies every few years or if she gets worse. I got worse in my late 30's, when hormones tend to change again.
I hope she continues to do okay. Does she realize that MG is all about alternating activity with rest? I sure hope you tell her how bad heat is!
This isn't your fault, even though I know that's how Mom's think. I had to keep telling mine that it was NOT her fault. Sometimes life just happens this way. If you guys do have a CMS and not MG, it completely changes how you treat things.
I hope you both can deal with this and try to adjust.

Annie