S.T.
I'm not a parent of a special needs kid - but I have 2 close friends with autistic sons and other friends with kids at various spots on the Asbergers continuum. Our church is very friendly to special needs families, kids and adults. We have sunday school classes and one-on-one aides if needed, we have special "Hugs" programs about 4 Saturdays a year that draw hundreds of people form the metro area.
What I've found over the years is that there are people who are willing to learn and are plialbe and open to your instruction and they will be valuable allys to you and your family. And there are others who think they know everything - and that kids like your son just need "their" brand of parenting to be the perfect kid. They will never read anything you give them since they "already know everything they need to know". Ignore them - they won't ever be converted. ;o)
You are doing a fabulous job for your child and that's all that counts.
(Also, BTW, one of my friends took her 6 yr old autistic child off all gluten and artificial stuff and he's improved quite a bit - her other son never had the senstivitiy but he's on the same food plan to be supportive to his little brother.)