How do you know when you have OCD?

I kind of thing I might have a mild case of OCD, but I'm not sure. I constantly have to redo things if i don't do them exactly how I picture them in my mind. If I touch or grab something the wrong way I have to go back and touch it how I wanted to. Whenever I touch a light switch or the mouse pad on a laptop or several other things, wrong I have to go back and touch every part of it or I freak out. I try to ignore the urge, but sometimes i can't because it drives me crazy. Does anyone know how to tell if I have OCD, or is it just something weird about me?