levora .15-.30 mg

I have been on this birth control before, and just started taking it a week and 2 days ago. I never once before had spotting or terrible nausea. Before I started this my boyfriend and I had unprotected sex a lot. But the thing is, I had a pregnancy test at the doctor office last time we did to make sure I was okay. So I shouldn't be pregnant but is there a possibility it could be? Bleeding isn't heavy. It was dark brown and then go little pink and then a little red by still super light and now it getting back to light brown. It doesn't feel like my period..