Implantation bleeding or just my period?

I'm taking birth control. I forgot to take it one day about 2 weeks ago. When I noticed in my pack a few days later, I took it in the morning. (I normally take it at night so I took the missing one in the morning and the current day that night.) I wasn't too worried about just missing one day, but now for the past 2 days (3 days before AF is due) I started having brown spotting. I figured it was just random break through bleeding but there isn't any clots and I know that's a sign of implantation bleeding. I'm planning on taking a test when I'm officially late, but it's killing me. My husband wants a baby but I'm not ready.

P.S I don't have any other symptoms like morning sickness or dizziness. In fact, I just started cramping. AF is due tomorrow.