@pitchforksandflamethrowers
It is difficult to understand someone that has no concept of other people as people with feelings and needs. It is as if they are the only person alive and everyone else is either a cardboard cutout or a robot they get to program. Combine that with an unusually strong will, and woahhhhh.
If she is STEM then perhaps set theory is a concept she can follow. Each person a circle with needs. (Feelings might be too foreign a concept right now). Needs need to be met, so the circles need to overlap. How big is the overlap, what goes in it?
A Rudyard Kipling quote is useful:
" I keep six honest serving men (they taught me all I knew); their names are What and Why and When and How and Where and Who."
There are also more: What is it not, Why is it not, When is it not, How much/often is it/little/infrequently is it not, Where is it not, Who is it not.
Using these to drill down and find specifics may help.
Because she is so different, she may have no idea that reasons which to her are blindingly obvious are remote to others. If there are sensory issues, it might explain the dog - smelly, licky, noisy, yuuuuk - everything ramped up to unbearable. A baby screams, and it might be like someone driving a hatpin through her head. It might not only because she doesn't want to share. There might be other reasons.
Demand avoidance - because someone is already so loaded up inside with internal demands they can't handle the external ones. If her diet is rubbish, then she may have a constant background of gastric pain that lowers her ability to cope - while being completely unaware that it's a thing.
One more thing - for you:
"He who faces no calamity gains no courage". Rudyard Kipling.