Could this be a mild case of ADHD? Or something else?

I've never been able to pay attention in class. I fidget, stare out the window, doodle, work ahead. I can't just sit and listen. In fourth grade, I would literally get out of my chair and sit on the floor and do whatever. I'm very unorganized, and get distracted by other things. I can't sit still. I'm always moving my feet, legs, or hands. I can't concentrate on school work. This has caused me a lot of problems. I always do it, but I'll be up really late doing it, and wait until the last minute. I change the subject a lot when talking, and have trouble holding 'normal', 'serious' conversations. When people don't listen to me and do things right the first time, I get extremely mad. I'm really jumpy too. I get A/B's in school. I'm in the highest level classes. This is why I don't think I have ADHD. I'm actually pretty smart, but don't study, or apply myself at all. I'm lucky to have A's and B's. I feel like the more I go on, the worse it is. I'm in hard classes this year, and I feel like I need to be able to focus, and work. Plus, I really want straight A's.

So, what do you all think?

I'm a girl, and I'm 15.