Well, if you do have ADHD - this is an ADHD forum, it could be related to that. It is very common for people with ADHD to need to move.
Studies have shown that fidgeting helps with concentration - http://www.additudemag.com/adhdblogs/19/11285.html
I know how your feeling,I have ADD too and I don't do it to the extent that you do but when I get excited or bored I fidget with my hands a lot. I talk with my hands a lot too. Its definitely normal for us so don't worry, you are not a freak, if anyone tries to tell you otherwise I'll come over and kick their butt! Those people **** me off, along with the people who tell me to snap out of my depression, that I don't have anything to be depressed about, Umm, hello, it's a chemical imbalance in the brain you idiots lol,but anyways I don't know if you have gone to your doctor or not but they have a few different medications cuz there are actually 7 different types of ADD so if it gets to the point where your hands bother you, try talking to your doc, and if the Med doesn't work, don't give up it just may not be the right one for you, hope this helps you and keep on drawing, art is a beautiful thing!