Experience with taking SSRIs before and after PTSD diagnosis

My therapist has directed me to seek treatment for PTSD stemming from an incident that happened earlier this year. The psychiatrist I met with has directed me to take SSRIs. I have taken, like, 6 different SSRIs/SNRIs to treat depression, and they've never worked at all. I don't want to take another SSRI when they've consistently failed me in the past, but the new factor here is a PTSD diagnosis.

Does anyone have any experience with this, taking a medication that previously didn't work because of a new diagnosis? I can't find any leads for a scenario like this, and I really don't want to take SSRIs again. I felt so much better after quitting my last one, Effexor.

I understand that this question is a real stretch for non-pharmacologists, so I'm just wondering if anybody else has gone through this scenario. Thank you.