Brown discharge, implantation bleeding?

I think it could very well have been implantation bleeding, especially since it was brown. Brown, is old blood, not new/fresh. So it makes perfect sense. And if you are a week and a half late, it sounds like there is a good chance you are pregnant. Every woman is completely different when it comes to how early you get your positive result. Some women have to wait quite a while longer than others, for the hCG to build up to a detectable level in their system. Just make sure when you test again, that you use first morning urine because it is the most concentrated. You can test again now if its been a good week since your last test, your odds are pretty good of getting a more accurate answer since hCG doubles every 2 days. Good Luck, and Lots of baby dust your way and mine!