maybe its not a mental disorder at all--my 10 yr old has never slept good. we have a simple home life, theres no extreme chaos, but still, he wouldnt stay asleep, he would wake up 2-3 times a night screaming without an explanation. well--he had reflux when he was born, and they didnt tell us much we could do to help him--i dont know if it was a bad doc or what, but anyways, my daughter has it too, and ive learned alot about it--and they dont always completely outgrow it. we changed some eating habits and tipped his bed, and for the past 4 mos, hes slept!!!
I expect your daughter is suffering from anxiety. Treatment for anxiety is intervention, therapy and/or medication. Sometimes, medication is the only answer after all other avenues have been explored. I might suggest you ask for a referral from your family physician for a child psychiatrist, or child neurologist, or any mental health specialist with experience in anxiety disorders. It appears as if the psychologist you are using is not sufficiently experienced in childhood anxiety disorders. By the way, if your daughter is suffering from anxiety, this disorder is highly treatable, but it will not go away nor will your daughter outgrow it.