I guess my question is this: what are you hoping to gain by knowing if your son is AS at this age? To my eyes, the term is only as useful as what it can get you, and for us, that didn't really apply until kindergarten. But if he is falling behind in some important developmental milestones, you may wish to have help sooner. Or if you feel you will be needing services, this can be a good age to start getting qualified.
For making sure he hears you, have you tried touching him or getting his attention visually, before speaking? I found this helped a lot with both my children (one NT, one AS).
As for understanding your child, each AS is different just as each NT is different. You've already tuned into him well for some things, like the blanket, so keep doing more of the same. It is difficult, I know, but we can discover quite a bit about our kids by observing and taking notes (mental or paper, depending on how your memory is).
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).