HELP!!

I took a preg test on Sat. when my period was due and it said positive. I started spotting brown blood Sunday with light cramps. Monday I bled just a little red and Tuesday it was super light. Today, I tested on 2 diff tests and they both came out negative. I was due for my period on Saturday but this wasn't enough bleeding to be my period which usually lasts 4-5 days..Anyone else experience this and are still pregnant???