advice! how can I get a diagnosis for my daughter?

Hi!

My daughter was born premature, at 24 weeks, weighing 1.9lb. After a difficult start, I still find my self fighting. 

My concerns started when my daughter was at play school, she is now 12 and at secondary school. We still have regular pediatrician reviews, and have input from many other agencies. I am constantly told that she is on the border of diagnosis. Everyone agrees "yes, she probably has Autism, cerebral palsy, dyslexia etc because she was so premature" but she doesn't seem to tick enough boxes.

She does have a diagnosis of 'social communication' difficulties, and has received various counselling sessions, and support through school and other agencies.  

As she is getting older the physical and verbal aggression is getting more manageable, but the anxiety, repetitive reassurance and questioning is increasingly frustrating!

All of this behaviour is only ever seen at home, and with some close family members, school, although are very supportive, can not believe the girl they see in school is the same girl we see at home. 

I'm not sure if I am looking for advice or just wanting to vent!