HI December

Go to your GP and get it checked out, for your own piece of mind and because if it is autism wonderful things can be done through early intervention.
The quickker you get onto it the better.

I've worked with autistic kids for 10 yrs+, when you mentioned hand flapping it was a bit of a flag for me, as it is fairly common in people with autism.
Does he walk on his tip toes at all?
Obsessive about certain things, repetative in tasks?

I am no medical expert and I obviously haven't seen your son, but I am a big believer in mums knowing when something is just not quite right with their kids.
If you don't think something is right then go to your GP and seek their advice, if your not satisified with them then go to another GP or get a referral to a pead.

There are many varying degrees of autism spectrum disorder and no two people are absolutely alike.
I've met many wonderful children and adults who happen to have autism and they are great people, they just have a few more challenges than the rest of us.

Best of Luck
any other questions I'll do my best to answer as best I can.

..Laura