Unfortunately, what you're asking is basically for us to predict the future. I wish I could tell you that you'll be completely fine in X amount of time, but the brain really doesn't work that way. It depends upon how susceptible you are to marijuana, how much was built up in your system over how long, how long it takes your body to metabolise etc etc etc.
The worst case scenario is that you never get back to exactly how you were before. Unfortunately that is the reality for some. The good news is that they are in the minority and you should keep improving with time, hopefully.
I wish this went without saying, but IME it doesn't, you really should stay away from marijuana and all other drugs in the future in case you get worse. Unfortunately there's no way to know who will be the ones who can take drugs recreationally and be fine, and who will develop lifelong MH problems, and who will be in between those two extremes. Best not to gamble, IMO.
Also, as an FYI, remeron/mirtazapine is a tetracyclic antidepressant, not an antipsychotic, which seems an odd choice if you were diagnosed with drug-induced psychosis, unless they thought your issues were more depressive driven, idk?? Anyway, the important thing is that it is helping you.
I hope that you are able to get back to how you were before this experience
*Willow*