It makes me feel a little less useless for having such a low stress tolerance. I can't do what I think I "should" be able to do and still remain stable. I hate that.
Don't worry, we all go through it. Took me years to sort that one area out progressively... and I still struggle at times, relapse, identify that I have done so, inact corrective action again.
I have tried to work and study in the past, failed on both accounts miserably, but didn't give up. I just acknowledged that I needed more self work, now I am trying again, study first... then I am hoping I can cope with work. What I learnt last effort is to prioritise my days better, ensure I don't create a self destructive thought pattern, ie. I have all these things I have to do, study, assessments, clean, cook, iron, wash the car, etc etc... instead I isolate and allocate specific time to tasks, including rest. As a result, I am functioning better with PTSD... though I also accept that I would fall over including work full-time, as even renovating a house, I fell over ill most weeks due to stress, and I love to build and renovate.
Acceptance of our new limitations is a big part of PTSD, though also we must find and push our boundaries at the same time, and just because we fall over, doesn't mean our boundaries can't be pushed further, it just means we must push gentler next time, and aim at smaller, more incremental expansion to any limitations we have.
Baby steps, pretty much!