Personally, I would be more concerned with why a GP would tell you such a thing. Realistically, a client or patient is a source of income for any working professional. That's just the way things work. Of course some are in it just for the money but certainly not all.

4 and 6 months is not a long time to be in therapy for PTSD. It can take a long time before one starts to see changes. Maybe a better way to evaluate if therapy is working for you is to figure out if you get any relief or benefit from seeing you therapist at all. And are there other avenues for you to pursue to get the help you are seeking?

As for the pdoc, do you see him/her just for meds? Would your GP be willing to prescribe meds so you could save money by cutting out the pdoc?