Thanks for the replies. Sorry I didn't manage to get back yesterday.
As far as I know there are no CP concerns. Nothing has ever been raised or suggested over the 18+months she has had these symptoms. However my experience with ds last year should warn me than things can blow up out if the blue.
Dh specifically raised the question of out of the family abuse with the psychotherapist. We have no reason to believe this has happened but in view of recent revelations, you never know. She said that she didn't think this was likely as she had seen no signs and it is one of her areas of expertise.
As for whether I accept the diagnosis or not - I think I am rather agnostic. She has been investigated quite thoroughly though not exhaustively. Her symptoms can be a bit odd so I can see why the medics think no physical cause. On the other hand there really isn't any obvious psychological cause either.
I know that I am influenced by my own experience. I developed a ME type illness in my mid 20s. I also had a lot of symptoms that are not typical of ME. After many investigations I started psychotherapy with a good therapist and it did make an enormous difference. However I still had a lot of symptoms and over the years I have developed more. Nothing has come of neurological investigations and I have decided to stop trying to get a diagnosis.
I feel that in both dd's and my case it is not that we have something incredible rare which could be diagnosed if only we could find the right expert but that given the current state of medical knowledge and more importantly, methods of working, we have something undiagnosable.
That's not to say that dd may not have been impacted by e.g. her brother's severe OCD but she clearly doesn't want to talk about it at the moment.
I can't see a way forward at the moment but she clearly does need maximum support with her very real physical difficulties.