Gosh lillypond, i really really feel for you and your present position. I honestly wish there WAS some question about my own son's dx as it was a terrible blow, but thats another story.
All i can say is that since my son was dxd I have learnt a LOT about asd, as i am sure you have. there is NOTHING written in stone, and doctors who say they KNOW it all, basically do not. Human beings are complex creatures and especially children. My own son is making such huge leaps and bounds with ABA and biomedical intervention that I am very hopeful that he will be able to shake off his "label" at some point. I dont particularly care about the label as it gets him services and nothing will give me greater pleasure than going to my original doctor and telling him that his original prognosis regarding my child was "poor".
however, in your situation, as i said, it must be real hard to just sit back and wait. autism cannot be, in my opinion be talked about "alone", there are so many other factors involved, the world wide hysteria of "labeling" and drugging kids, the politics, the money, the greed, etc etc. I have come to take it all with a great pinch of salt. I dont care what anyone says about my own child cause i know where he is going and i have done just about everything i possibly can to help him, despite the NHS/DHSS/GMC!
"Experts" have their place, but in terms of your own gut instincts, no one knows him better than you. I would be very worried in your circumstances, that services may be taken from your son. Of course you would LOVE to have the dx removed, but where does that leave him in terms of help now and in the future? Nobody knows really what kind of help our kids will need in the future, particularly when the state is so unwilling to provide that help NOW when they need it. As i always say, i dont care if they call my son the "creature from the green lagoon" as long as he gets the services he needs and deserves.
In terms of the refrigerator mom crap that may have been insinuated, what a load of bollocks. First "they" say its genetic, then they say its our "fault", what do they really mean, what do they really know???? Not much really.
My son too, is an only child who did not get much interaction. Like yours, he was content on his own and didnt demand like other kids without the label. Never never NEVER blame yourself! I did this for some time and then i just wised up after reading and listening to other parents. Autism is a complete mystery and no one particularly someone within the health service, has any right to make any judgements about where autism comes from.
rant over love, but keep your chin up. Just keep on fighting for what is your child's right. Love him, hug him and tell him that you will do everything in the world to help him, despite others. He will know what you mean. Whether or not he loses his label, he is still the same little guy inside. Labels are man made, children are not!! Good luck and god bless.