No way it's my period!

I put this up here on Thursday. I had this weird brown spotting, then Friday filled up a tampon with the brown "blood" then 1/2 a tampon with the brown "blood" yesterday. And today it's totally gone. I put a tampon in around 5 yesterday and just took it out and there wasn't a drop on it! I can't believe that there's a chance this is my period. Since I was 9 my period always comes on the 15th and its bright red and it last 5-6 days.