My issue is that I can do mental work I used to do, but not RELIABLY, and also not for more than realistically only about 8 hours a week 30 weeks a year, given how my classes have been wiping me out and requiring all of the break between semesters to recover from. It's not enough to help me live.

Yep yeppp. I have been very very fortunate to have a wfh dayjob with flexible hours and even with that, sometimes I’m exhausted to tears after working just a few hours. I’d say I can’t imagine adding the stress of the us healthcare/disability system to that except… I can imagine, and it’s awful