I have been having pregnancy symptoms, but now experienceing bleeding.?

The first symptom was nausea, the i became extremely tired, all the time, and still am. My are extremely sensitive and sore, it started with just the nipple area but now it's progressed to the entire . I've also experienced mild cramping. My last MP was from feb.2 to the 6th. So it isn't do for another week at least. But this morning, I had a light amount of dark brown discharge, but my period isn't do quite yet. It's nothing major, just a pant liner amount. I've also had lower back pains. I've been a little more moody then usual. I figured that i was pregnant, but i've had two negative test, is it possible that it's just too early for a HTP to pick up the hCG? These are traditional symptoms of pregnancy right?