I don't know if I had my period or not?

I'm 13 and I don't know if I had it yet. I heard that if you get hair in your arm pits and "down there" then that means you already had it? I also got something that I think is called a white discharge I'm not sure if it is but it was thickish and squishy. If it is then I also got a brown discharge a few months ago. And what age do girls get their periods? Because almost everyone I know already got theirs...I sound so pathethic asking these questions...