Period questions. Girls only?

I don't know if I'm having my first period. I've been having moe of a mucusy thing coming out. (clear, usually sticky) for a few years now. I'm 13 and yesterday I had some kinda brown stuff in my underwear right below where the mucus usually comes out. I know periods are red so I'm confused. Yesterday it was a few drops and today i had it in my underwear but it wasn't soaking through. It kinda burnt after I discorvered it in the bathroom during the second day. Am I having my period?