I also have MDD in addition to PTSD. I think it does aggravate things.
I have been exactly where you are, Trying. I had to get on it in 2009. It broke my heart. I was a wreck over not being able to work anymore. I never even thought about retiring, just thought I'd keel over someday at my computer. I'm still on it, and probably will be for the rest of my life.
But there is some hope . . . my disability lawyer (yes, I got turned down the first time, like most everybody does) told me that most people improve once they get on it, because they don't have all the stress anymore And in fact, I did improve after a few years off from any work whatsoever, of hard therapy, meds, and learning to cut down on stress in my life.
One of the hardest things I've had to do is accept that this is where I am. I still struggle with it some days. But a few years ago I was able to start working again, albeit very part-time. I can usually manage about 20 hours a month on average, which isn't great but it's all I can manage and it's something.
Hopefully, once you get a couple years off from that stress and just focus on your healing, you might be able to do more again, too. As my lawyer and my therapist told me at the time, getting better is my job now. :hug:s