My oldest son is autistic, and I married a Twin and my niece is Autistic as well. My son who is 14 and starting high school this year does the stemming with miniature toy figures meant for a child much younger than he is. None the less he is still growing and maturing in his own way everyday. I can't wait for the day this Site provides real private messages because I would love to send you some phone numbers of excellent resources. All I can advise you do for now is to continue to educate yourself on your sons limitations and understand that there are tools that will allow him to overcome most of them. If he is in public school make sure they ad-hear and comply to your child's IDP, and if possible visit a nutritionist to change his diet if necessary.
I wish the best for you and your family. Take Care and thanks for sharing your story we all need a outlet sometimes.