Just a little info from my recent experience. I had 3 +ve HPT's followed by a -tve. This was at about 5 weeks. I am never late and I was havng pg symptoms. I then bought a digital one that only detected higher levels of HCG which came up +tve but started to spot then bleed a couple of days later, eventually ending in m/c at 5wks 4 days. The rule of thumb is that the longer that time goes on the darker the lines get and if thats not happening or you get a -tve like I did I think it probably shows that things are not as they should be. I hope I am wrong in your case. Good luck with the BT.