Hi, Mom 0405. Your story sounds very familiar. Actually did you copy my first post? hehe Due to all the OEs of my DS6, we decided to homeschool him. Preschool was exactly the same as yours sounds. Loud noises, kids squirming, sitting still to learn were too much to ask. No diagnosis fit. His preschool teacher was awesome though and gave him the highest math puzzles she could find. Not surprisingly he did great after that. A lot of posts have been posted lately about processing speed and timed tests. They might help. Also I suggest (in addition to St Pauli Girls recommendations) The Mislabeled Child by Dr Eide. Where you DS is different in regular classrooms, he will fit right in here. Welcome.
BTW-There is no way "Because I said so" would work for us either.