No period, brown discharge, and negative hpt
OK so today I found discharge in my underwear and I thought that I might have started my period. I was in a hurry at work so I didn't get a chance to really see and I wasn't worried at all. A little later I noticed that the discharge was not red like I thought it was. It was a dark brown color and I wasn't bleeding at all. I was really freaked out about this and told my boyfriend as soon as I found out. We decided to go buy a pregnancy test to make sure I wasn't pregnant. I am supposed to start my period very soon (some time this week but I don't have an exact date) I'm on birth control and we use condoms most of the time. I'll admit the last two times we've had sex we didn't use and condoms. I took the hpt and it turned out to be negative. I've heard that the brown discharge could just be old blood but that it could also be implantation bleeding. I don't know what to do. I'm going to take another test in a couple of days but I need some feedback in the meantime. Could I be pregnant?
Please help.