Autism can be diagnosed at any age, typically after 18 months, with the proper doctor/team. PDD-NOS is typically what a Dr would say if the child, at the time they used this diagnoses, would have atypical Autism, vs Classic Autism or Asperger's. PDD-NOS back then wouldn't have been covered under many insurances. I found this on the web about it "Some developmental health professionals refer to PDD-NOS as “subthreshold autism." In other words, it’s the diagnosis they use for someone who has some but not all characteristics of autism or who has relatively mild symptoms. For instance, a person may have significant autism symptoms in one core area such as social deficits, but mild or no symptoms in another core area such as restricted, repetitive behaviors." I highly doubt she was PDD-NOS when she was diagnosed, and if she was IDD would have been primary diagnoses because she's got classic Autism.