I found out about my son at his 12 month checkup when he didn't hit the 12 month milestones. He did flappy hands alot too though. Here is a link for a test to give you an idea of their chances of having it. https://www.autismspeaks.org/screen-your-child
If he's showing empathy and affection then I think you're still on the neurotypical side. It sounds pretty developmentally normal to me, but your pediatrician will tell you more.