A HPT typically detects pregnancy 2 weeks after conception. Its possible you ovulated late in your cycle and are pregnant buts its more likely you are just having an off-cycle. In any case, take a test in about a week.
I agree with julz, if you are still getting a BFN in a week I would go to your doctor and perhaps they can tell you what happened. There could be a slight chance that you are pregnant as some woman do spot during their pregnancy but if you are getting BFN than I highly doubt it. Hope everything works out for you, good luck.
Well, to me doesn't sound like it. Unless, you ovulated later in your cycle, and you've now been experiencing implantation bleeding. You're already around 2 weeks late for your period so I would go ahead and take another test, see what it says. If negative test again in a week, and then if you miss your next period make an appointment with your Dr.