When DS9 was younger there were definitely some things that had me wondering a little if he was ASD. Note that I'm not a psychologist so some of the things that made me wonder might be based on inaccurate stereotypes so take it with a grain of salt. In the end he is HG+ (we don't have extended norms here so hard to say how much +) and 2E but his second is in written expression and I no longer suspect ASD (and he's been through 2 full psych ed evaluations and they haven't suspected it either).

Here's some of the things that had me wondering at various points...
- delayed speech - at 2y3m he had less than 10 words (and I use words generously - "meh" was milk) and that was with 8 months of intensive speech therapy... A year and a half later you would have never known it and he was shocking people with his crazy vocabulary though.
- sensory issues (tags on clothes, certain fabrics, etc - he's still pretty picky about this stuff)
- obsessive fascination with topics - dinosaurs, then black holes & particle physics, now he's branched out a lot more
- routines - dropping him off at school up until grade 2 involved a 17 step handshake/wave sequence, it was crazy
- upset if anything changes - so many examples here but this is improving with age
- eye contact - this is something that we've had to focus on teaching him (although admittedly this is something I have to think about and I kind of think that most people don't, but maybe I'm wrong there). DD by comparison just does it automatically and we've never said a word.
- anxiety
- sleep issues (more when he was younger, not bad after about 2 or 3)
- has issues with people that break rules or aren't logical - kids at school often fit into this category

In our case I can definitely understand the confusion.