Welcome!!! And sounds like your DS is very similar to my DS, now 5. We have not had him tested yet, but I imagine adding a bit of OE to his GT will be the diagnosis we get when we do test him.
This is an amazing place, and while there are many differences among the kids' abilities, strengths, struggles and whatnot, the fact that there are REAL people who understand the REAL struggles (and accomplishments) of dealing with a "different" child makes our own experiences with our GT children (at least mine) much "easier" (or at least "normal").
