Could I be pregnant?

My husband I are just starting to try and conceive. I was sure I was pregnant. My breasts were abnormally sore, leaking, I was nauseous and frequent headaches. My period wasn't due until Wednesday, and I had taken a negative test on Saturday morning. I started cramping in my back on Saturday night. Woke up Sunday and re tested with a bfn. Then Monday I woke up with my period. Very mild cramping. The thing that is striking me is how abnormal it is. My period is normally pretty heavy and I get intense cramping. The kind that hunches you over. I am bleeding more than spotting, but it's really dark brown and light pink and I have yet to soke through a pad or tampon. I haven't needed any pain killers for cramps yet. It is too much for implantation bleeding and too little to be my period. I haven't tested again since it started. Thoughts?? Oh and my boobs still hurt.