Confused

Ladies, I took a test Tuesday (14dpo) and it was a BFP!! I was so exited. I took one again this morning to see if the line had got darker. When letting it sit for the 3 minutes it was a BFN.. I’m really confused and just don’t know what to say. I was supposed to start my period yesterday and it never came. Has anyone else had this happen and have suggestions. I have a doctors appointment next Thursday but am just really at a loss of words. Below is the picture from Tuesday!