Prepared to be told I'm BU, I feel bad even writing this but I am a little concerned about DS and not sure if I'm just being weird.
He's 3 (just) he doesn't speak in sentences properly, he manages 3 words here and there and a lot of them are only understood by me or DP as he doesn't pronounce them properly. He's generally very giddy and all over the place and it's extremely hard to get his attention when we're not at home.
In comparison to other children his age we hang out with he's got virtually no attention span he runs around like crazy (especially at soft play) and it's very hard to get him to stop and listen. Other DCs happily walk holding their parents hands and even chatter a bit whilst he tries to rip away and run around.
Same goes for teaching the basics like "sharing" other children seem to kind of "get it" they might not be too happy but will share/let another DC have a toy or whatever at the parents encouragement, my DS just shouts "no! mine!" and bursts into instant loud crying. Even much younger DCs often let him have toys because of the way he gets 
I've recently watched my friend have a proper conversation with her just turned 2yo, something I can't even dream of with DS ATM!
And what concerns me the most is his crying, as soon as he starts crying he starts coughing, depends on how much he manages to work himself up he sometimes even ends up slightly retching multiple times despite my best efforts to calm him down.
Potty training is also out of the question ATM.
I expected him to talk a lot more and be a bit more "with it" at this age.
AIBU?