Could I be pregnant?

Ive been on sprintec four year and miss a pill by a couple hours maybe once a month. My boyfriend and I use condoms 90% of the time but we have a decent amount of sex. My last period was relatively light for me, only two or so tampons a day and ended two days before I was due to start my next pack. I also started bleeding old blood the last day of my active pills before my period. What’s up with this?