S.,
I have two girls with Autism, and I am also educated (you will be too if this is really an issue for your family) The first place to look is www.autismspeaks.org They have an early check list. Your pediatrician should be screening between 18 months and 2 years.
What is worrying you? There were things that we saw with our daughters very early that we now look back on and see were autistic symptoms. If you want to bounce specific things off someone, let me know and I would be happy to share. The next step, if you really suspect is to make an appointment with a developmental pediatrician, located at any large children's hospital or other hospitals with developmental clinics.
One thing to remember, if you have met one child with autism, you have met one child with autism. They are all very different. Be careful not to approach this looking for that one thing that will disqualify him, you won't find any one thing and you could be very wrong. Autism is a spectrum disorder, it ranges from severe to mild and everything in between, some kids have trouble in many areas, and some just a few. Language, social, sensory and behavioral issues are what you are looking for. Also, it is tempting to stereotype what you are looking for according to what you have heard about what Autism looks like. You are looking for atypical behaviors and developments in these areas, not necessarily rocking or total lack of language or no eye contact at all.
Take a deep breath. It is not a today emergency, even if you decide that he needs to be evaluated, it will take months before you can get him evaluated. He is young, and if you have something to worry about, you will be getting pretty early intervention.
Beware of people who will tell you that their cousin or their neighbor did the same thing and is now a rocket scientist. If you think that there is a problem, find out for sure from a professional and don't "wait and see." The biggest thing you have on your side is his young age, early intervention is the best you can provide.
M.