I also had a child who was diagnosed very late. Partly because I was kind of parenting in isolation and didn't know some of her quirks were extremely unusual. For example it took me about 6 months to teach her the correct use of personal pronouns, ie that she should refer to herself as “I" and to me as “you". Let me tell you those endless conversations with an 18 month old about who was who were confusing for me let alone her! But at that age everyone we met was telling me how wonderfully she spoke, it would never have occurred to me that she need a speech pathologist. She had lovely diction, a massive vocabulary for her age, (mostly) excellent grammatical sentences, etc. I had no idea she had a significant and diagnosable speech issue. She also never really had an eye contact problem. She generally flapped from happiness not distress…
At 15 she's doing great and most people would never EVER guess she has a diagnosis, and that is due to being gifted, a girl and years of careful management, not because it’s not real. I am SO glad she does have a diagnosis because as good as she looks life is still HARD for her and the self awareness of where struggles come from is invaluable. And with the value of diagnosis in mind, if I could do it all over, I would get the diagnosis before doing all the therapy and intervention that we did, which made the later diagnosis so very hard. After years and years of hard slog that had all really helped enormously, if your kid is still has big struggles and you realise they need that diagnosis, you don't want to be sitting across from professionals who are saying "Mmmm, we can sort of see it, but she's doing so well...". I had to actually point out to some of them that if she had a diagnosis before all the interventions, and we were sitting here today having this chat about where she was at, you would be saying "Congratulations, your child is doing brilliantly, it's all working really well, they do of course still have Aspergers and always will..."
