"Fake it until you make it", stolen from the AA big book (from memory), but applicable for all that... Tell your school the problem, get them to understand the issues, then seek support when things are going wrong.
I so agree with you on all you said. especially the "tell your school the problem." I'm 67 years old and had ptsd since I saw my sister murdered by my step-mother when I was 7 years old. Back in those days they didn't call it ptsd. but when I was 22 my doctor called it ptsd. he said it was as though i'd been in a war, with all the violence and trauma i'd been through in my short life. A lot of shit happened after that, but the good news is, it does get better.
Once others can understand what PTSD does to you, they begin to want to help. Not everyone, but most do. I learned that once i knew all my triggers, and my reaction to them, I could control what was going on (for the most part). Yes, i still have some bad times, but not nearly as many as I used to have.
Sounds like you are getting some wonderful support here. Take care.
Safe-now