You should definitely find a doctor who thinks s/he can help your daughter. As you said they diagnosed it as psychogenic because they couldn't pinpoint an organic cause. However, a true diagnosis of psychogenic non-epileptic seizures (PNES) involves ruling out
both epilepsy and organic causes for non-epileptic seizures (NES).
One of the important possible causes of NES is migraine. So if you doctor says that it's a possibility but doesn't feel that it's worth exploring then she probably is not approaching the problem correctly (Of course she could mean that she feels that migraines are so unlikely that it would not be justifiable to spend time looking at them that could be better spent looking at other causes--but this doesn't seem to be the case.).
Also, you mentioned that she has been falling a lot. Does she lose consciousness, even briefly? If so that is an indication of a possible organic cause. Does she have erratic uncontrolled movements (automatisms) during her seizures? That's another sign that points away from PNES.
How did the doctors at the hospital determine that the seizures that they observed were non-epileptic? If your daughter experiences the seizures often enough for a clinician to monitor them then you may want to ask about "Long-term video EEG monitoring"
. Apparently it's an invaluable tool in confirming or ruling out PNES.
One final thought--what type of therapist is your daughter seeing? Considering the circumstances I would guess some sort of psychoanalyst. If she's not getting anywhere with the therapist you may want to try seeing a different therapist, perhaps with a different approach, behavioral for example. I don't say this to cast any doubt on the reliability or skill of her current therapist. It's just that each therapist-patient relationship is unique. As someone who has seen more therapists than I can count with my hands it's been my experience that even the therapists that I've liked the least have helped me look at things in a different way than the others. I also have a disorder with no observable organic cause (daily persistent headache) and for several years one of the goals of my therapy was to rule out the possibility that the headaches were psychogenic. Every one of them has confidently ruled out the possibility but I still am able to deal with the nonstop headaches more easily with their help. What I mean to say here is that, even if there are not "subconscious stressors that could be causing these episodes", it's quite likely that there are some subconscious stressors that affect
the episodes. And if that's something that you might be able to control then it can only help.
BenP.S. I found two good journal articles about PNES. I can't link you directly to them but send me an email if you'd like to take a look at them.