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Nope, there's not a thing wrong with how you're doing it. I do the same thing.
FICO generally does not like to see all of your CC reporting as 0. YMMV though.
Have you ever tried to let one report a small balance to see what happens to your score? I wouldn't be too worried to try because if you don't like what happens, your score will go back up when you pay it off. FICO has no memory and is scoring you for what is on your CR at the time.
That's the method to get a little bump on your score, so to speak. I personally don't like paying any interest, so I just keep mine at $0.