When I have come off anti-depressants gradually, it has taken me 6-9 months, but that was because I had to reduce them so gradually, because I suffered such bad withdrawal effects. But since she went cold turkey 2 months ago, I would say from what little I know, that these drugs will now be completely out of her system. And physiologically she won't be having any effects from her meds. But it may still take another month or so for her mood to settle, without the drugs.
Whilst medications aren't a solution, and in fact can be shown to be detrimental in some cases, they can also be beneficial. Yes!! I know it's all a bit hit and miss to be honest.
You don't mention whether she is in therapy, and I haven't read any of your other posts, but if she has PTSD then it's pretty unlikely that she will just get better, without some degree of therapy. Specialist trauma therapy would be ideal, but it is also possible to do some self therapy work, using CBT techniques, and exposure therapy. Online therapy is also available these days.
It must be hard for you, because no-one can force anyone to seek help. The demon of PTSD is that you have to want to get 'better', and put in the hard work yourself. Very tough to stand by and watch, if she is self-destructive, but you should try to support her the best you can. I'm sure some other carers/supporters will be along to give better advice than I can, as a 'sufferer'.
All the best
CB