Sometimes I wonder if we have too much information at our disposal... I know I worry way more than I should and I know it's because I've seen something on Dateline or I read it on the web.
That being said, my son is now 12 years old. He always had his own little quirks, he was VERY active, sometimes a little hyper, didn't sit still too well and even my ex's new wife (who has two autistic children herself) tried to start labeling our son as ADHD or other things. She was constantly telling him he was "stimming". Because she was persistent and she pushed a custody case (now over and he's still with us) we did have him screened when he was 9 years old just to put the subject to rest. The psychologist stated he is a normal child with nothing wrong with him. (His teachers had already said this but now it's official- he's just fine!)
In fact, he is just highly intelligent. He's in 6th grade, accelerated GT program and straight As. He's in music and he has a small group of close friends. He's social and happy with who he is. He's not necessarily athletic but he's ok with that.
My daughter is 17 months old, talking in sentences, walking, hitting all her milestones etc. Everything you've said about your baby. She also does the opening and closing of her hands when she's excited though or wants to be picked up. She also dances whenever she hears music (actually shakes her head to the music if she's laying down when it comes on)
I'm pretty sure (but I'm not a doctor) that you have a completely normal child. :)
I'd also recommend, as a mother of a boy, you look up the following books. A lot of boy's behaviors fits some "ailment" these days but in all actuality most of boy's behavior is completely normal and in contrast, restricting it actually hurts male developement, not helps.
'The War Against Boys' by Christina Hoff Sommers- You can read the first chapter here http://www.nytimes.com/books/first/s/sommers-war.html
'Raising Confident Boys: 100 Tips for Parents and Teachers' by Elizabeth Hartley-Brewer This link is long but you can access the reviews and part of the first chapter here.
http://books.google.com/books?id=MhvK3ZZO3W4C&dq=rais...