P.,
Please know that you are not alone. Many, many parents are going through exactly what you are, my husband and I included. I could have written your request for help, word for word, and in fact I did to my friends and family in many emails. Your son sounds EXACTLY like our now 5-year old son. Our son is very bright and intelligent and knew all of his colors, numbers, letters, etc, very early. He was a very easy-going boy who talked easily with adults (such as when we are out shopping, like you mentioned), and who only started to have problems when he started preschool, when he was 3. He literally had not had any issues until after he started being with his peers for such extended periods. We were very confused and could not understand why he was acting so impulsively and defiantly, and also to our horror started hitting the other children in his class. His teacher was wonderful, fortunately, and told us that the main problem was his lack of social skills. After trying several different tactics, including tranferring him to another school with a smaller class, we finally decided to get him evaluated this past May, when he was 4. Our biggest worry was that he might be labeled, as several people who have posted have mentioned. In the end, we are so, so, so thankful that we had him evaluated because we realize sooner or later he would be labeled by his peers and especially by his teachers -- and it probably wouldn't be anything nice. He might have turned into the 'problem' child, if we hadn't had him evaluated and diagnosed, because now we have been able to directly address his issues and work on early interventions that already are making a significant difference. His early diagnosis was the best thing that could have happened to us -- and especially for our son's benefit, because now he has an excellent prognosis.
I don't want to scare you with our son's diagnosis; on the contrary I want it to reassure you that things could be much worse and that our son's diagnosis of Asperger's Syndrome is actually a gift. If you know how someone with AS, as it is called, operates, and if you educate yourself and the people who deal directly with your son, he can and most likely will have a wonderful, full life. I'm not here to diagnose your son. I am only writing to you to let you know that you're not alone in your experience, and that you can take steps to make your experence a positive one. You have to be your son's advocate. He depends on you to make the right choices for him at this age, and with help you will be able to make those choices.
First, I would highly recommend an evaluation for your son. We opted to go through our pediatrician (who gave us a referral to a child psychologist) instead of through the county school system. Once we had a diagnosis, we read about AS everyday until we felt like we really had a good feel of what it was all about. I would very highly recommend checking out the OASIS (Online Asperger Syndrome Information & Support) which has a huge amount of helpful information. I would definitely urge you to read a great article titled, "Asperger Syndrome" by Stephen Bauer, M.D., M.P.H, which you can find on the OASIS site under 'papers and articles.' The section titled, 'the preschool child' in his paper describes our son -- and it sounds like yours, also -- to a 'T.'
http://www.udel.edu/bkirby/asperger/
Also, the information about AS given by Wikipedia, although somewhat technical, is valuable as well:
http://en.wikipedia.org/wiki/Asperger%27s_syndrome
If you feel that your son is experiencing undue stress in his present class, you might want to consider withdrawing him until the evaluation is complete and you know what you're dealing with. If the evaluation doesn't turn anything up, or you don't come away with a diagnosis, I would still recommend transferring him to either another teacher at that school, if you feel he will benefit from that, or finding another preschool setting for him. His present teacher does not sound like the kind of nurturing person your son needs right now.
We were helped by a couple with a son with AS, who told us all they wanted to do was to help us the same way they were helped when their son was dianosed. Well, P., I feel the same way. All I want to do is help you in any way I can, even if that means just telling you you're not alone in your struggles.
Our son is now in a special needs pre-K with a fantastic teacher and he is flourishing with all of the great tools they have to teach him with. Like your son, he is very intelligent and relates well with adults, but around his peers he lacks the skills to be able to read non-verbal body language and to be able to carry on appropriate conversation skills. We have been told by many people -- the child psychologist, the school administrators, and his teachers -- that he will most surely be able to be in a 'regular' Kindergarten class next year, because by then he will have learned a lot of the skills he needs to function in a larger setting (right now his class has only 6 kids in it).
P., please feel free to contact me via email with any questions or concerns. I would be happy to talk with you on the phone, also. I hope I have alleviated some of your fears and worries, and even though I have probably said things that you aren't ready to hear, I know EXACTLY how that feels because that's exactly where I was earlier this year. We never want to hear that there might be something 'wrong' with our children, but if we realize that it's not something that our children are doing on purpose, and not something that we are doing 'wrong' as parents, that it is a neurological disorder that is treatable, then we have made the first step in helping them deal with this gift called AS.
Good luck, and let me know how you're doing.
J.