I had this same issue with FRER last cycle - I tested at 12dpo, 13dpo and 14dpo with FMU, and all 3 came up with a faint second pink line. I was pretty sure I was preggo but a little concerned that the lines weren't darkening with each day. On the day that AF was due, I took a digi and was a BFN - lo and behold AF showed up that day. I was so bummed!! I never had a blood test, but I had signs of pregnancy, and I was certain that I was. I think it was definitely a chemical pregnancy, which are very common. Most of the time people don't even know about them because they don't test early. This may or may not be what's happening to you - I hope not!! - but if it is, just know that they are very common. After the heartache from last cycle, I've sworn off early testing! FX for you though