Global Development Delay Diagnosis

Hi

My daughter, E, is 3 and was diagnosed with ASD about 6 months ago. I also think that E has Global Development Delay but when I spoke to the paediatrician about this she said that she hasn't because she isn't delayed in ALL areas of Development. E was then discharged from the paediatrician as she said E would be supported in the community (which she isn't but that's another story!).

I have since read up about Global Development Delay and realise that she would only need to be delayed in 2 areas of Development to meet the criteria for a diagnosis. 

Does anyone know the route to obtaining a diagnosis? Would I have to go back to the GP to get referred to the paediatrician? 

Any information/advice anyone has about diagnosis or GDD in general would be most welcome!

Thanks

Lauren