I refused to wear dresses and girly clothes when I was little too. I wouldn't even wear a bathing suit with a little skirt on it. When your nine-year-old starts insisting she is a boy in her mind, that's when you tell her that she can change that later on when she gets older. But for right now ("as long as you live under my roof..."), you are a girl.
LOL! I can remember throwing a fit because my grandma wanted me to wear a dress to school. I refused to go. Why? I wanted to play football, and you can't play football in a dress!