Surfbaby -- your DS sounds much like one of mine who got EI, talked and walked late and then just exploded. He's also into rules, can memorize anything, and can be a little intense for age peers at times. Yet he is social overall, well-liked overall by adults and children, and he does not have any ASD.
For him, I think he's an introvert and so can get overwhelmed by too much social stuff. He has high expectations for his own behavior, but this takes effort and it's hard for him to maintain that forever. He needs breaks to be silly at times.
In terms of memorizing, he was into counting and memorizing stuff as a preschooler. Now that he's been tested, he's just got a WMI >99.9 and he effortlessly takes in huge amounts of info and holds onto it. It doesn't make him Aspie, just really good at memorizing.
FWIW, based on board posts and from a position of never having met your kiddo, nothing you've said raises any red flags. He just sounds smart to me.
