I'm three days late..

Holly
Let me start by saying my husband and I have been trying to get pregnant for almost six months now. I have completed three rounds of clomid. I am now three days late but having light crapms. They aren't bad at all. Almost like a pulling pain.. I have the feeling like I'm going to start my period but I have never ever been late. My breast/nipples are tender and sore and have been for the last five - six days. Which usually my nipples are sore before I start my period. I took a pregnancy test Sunday morning and Tuesday morning and both were negative. I bought cheap pregnancy tests thinking it didn't make a difference.. 
Has anyone had these symptoms and still ended up pregnant?