I'm driving my self nuts!

I have a very short cycle. Normally 21 days sometimes 24 days. My expected period was supposed to be the 14th/16th depending on how AF wanted to be this month. It's now the 19th nothing. I had some pink hinged discharge the 16th so I assumed that was my period. Nope. Had some cramping Monday and a bit of brown yesterday (Tuesday) I've been taking pregnancy tests like a mad woman. Nothing. Am I losing my mind?!? Am I just testing too early? Could the pink tinged discharge be implantation? Please some advice.