"methodical in his approach to problem-solving tasks, sometimes losing credit for items because of exceeding time limits". In the WISC-IV composite information, his PSI is two standard deviations below every other index (verbal, perceptual reasoning, working memory).
It seems like the school should give him longer time for tests and assignments - even in the gifted program, as part of his IEP or 504. Is the school willing? To my mind your son belongs in the gifted program even though he might need extra time on tests - it's the depth of his thinking that matters, not the speed of his production.
The word 'mild' hit my eye also. My guess is that he has severe AS, but that he doesn't look like other kids with severe AS because of his very strong IQ. He probably doesn't 'look' as gifted as other kids with his IQ - but he is. I don't know if that helps, but looking at it that way seems to help at my house.
Stick around and keep posting - it sounds like life at your house is pretty stressful and I'll bet that you don't have many people to complain to.
Love and More Love,
Grinity
