Hi, I was in a very similar situation with my son. I started noticing he had some issues when he was 2. He went through a wide gamut of tests and was finally given a provisional diagnosis of PDD-NOS, which the psychologist basically said that she was giving me to put in my back pocket if I felt that having an official diagnosis would make him eligible for more services.
Since we've started the whole process, he has made amazing progress. He was (and will be this coming year) in a wonderful preschool, but like you, I am hesitant to say that he's completely normal (whatever that really means) at this point. He had been receiving speech and occupational therapy through the school district, and I have to be honest that I don't know how helpful they have really been. However, I have insisted that the school district leave his IEP open, and we will reevaluate his situation once he starts kindergarten in two years.
All that being said, my opinion is that receiving an official or different diagnosis probably won't make much difference in the services your son will be eligible to receive. I don't know what it's like in Kansas, but out here the districts are so strapped that unless my son receives a diagnosis of classic autism (Asperger's and PDD-NOS are considered too high functioning), they will not qualify him for additional services. He clearly doesn't qualify for that diagnosis, so we are sort of stuck as far as additional free services go.
If you are able to swing it, I think that a behavioral psychologist might be more helpful to you. At the very least, you can make an initial appointment and talk to one about your concerns and see what they recommend.
For me, what's really helped is finding books about dealing with children like this. There are a lot of books about "challenging children" - kids who are tough but not diagnosable. "Raising Your Spirited Child" is probably the most well-known, but I also found "Quirky Kids," "When the Labels Don't Fit," "Taming Your Spirited Child," and "The Explosive Child" very helpful. "The Oasis Guide to Asperger Syndrome: Advice, Support, Insight, and Inspiration" was also very informative as far as resources for your child, even if he doesn't have an Asperger diagnosis.
Good luck. I know this is so tough to deal with, and it's hard when your friends and family don't really understand the depth and breadth of your concerns.