Possibility of pregnancy?

What are the chances of becoming pregnancy if you take the first pill in a new pack nearly 12 hours late and then the second pill 8 hours late and then have unprotected sex on cd 6? I since have been very diligent with my pills, I just had a few incidents of thinking I had my pack or forgetting to bring it and not being able to access it. I am now cd 16 and my boobs are very sore and I have light brown discharge. Should I be concerned or am I most likely fine?