I have not read all the responses you've received, but wanted to offer my two cents.
Children at your son's age exhibit all kinds of behaviors, inhibitions and abilities. Because your son can read and draw doesn't mean much beyond the fact that he has a good mind and is eager to do things - encourage him in all of these things, but don't pressure him to be perfect in any of them now. The overall task of early childhood is physical and emotional development - help him with social growth and friendships, learning to enjoy things and to love and care for himself.
We have friends with an asperger's diagnosis for their son - and he is a difficult and amazing kid. He tries everyone's patience as a preteen but he is a wonderful boy and so, don't be afraid of the label -- just advocate for and help your child. Focus on what he needs to learn to be functioning well -- social skills, empathy, self mastery and the mastery of skills at an appropriate level.
And watch him - he is too young and outside of ECI to be dealt w/ within the school, though you could try to have in evaluated through ECI and your district for intervention services in terms of social skils. You could also take him to see a good diagnostician - insurance my cover this if you suspect a neurological problem. There are great neurologists in Dallas and they can help. His aversion and sensitivies will not be new to them and they will help you with getting him there.
Susan Istre works up at Shelton and has social groups for kids, as do other places. Once he is school age, the school will help you and you have rights within the system. There are many good private schools as well. I'm sure you know a lot of this as a teacher...
Bottom line: intervention to work on his needs is important, more important than a label at this time. Most schools use a response to intervention regime to understand what is going on academically with kids - and you can use an investigative approach with your son. Consulting a developmental pediatrician or a like professional yourself may give you the tools you need to continue your observations and provide your son the support he needs.
Our friend who have gone through this with their child went years without a true diagnosis - first it was thought he had ADD/OCD, anxiety. But aspergers, finally, made the most sense. Dan Akroyd has it, as many others have over time...(there is even a movie out on the topic), so take heart...and enjoy your child. But be prepared. These issues can drain a family of joy, resources, and contentment. If you can get close to what is going on and accept that your son has 'exceptionalities,' than you will be on your way, no matter what the answer is...early intervention is absolutely key to helping him and your family, though, no matter what is going on.