What Causes Early Menstruation With Prolonged Bleeding?

I have been on birth control for about three years. (Tri-nessa 28's). and this last pack of pills I accidently missed two of the blue pills in a row. My period came 5 days early and hasn't stopped yet. it's day 7 going on day 8 now. It seems to be a steady heavier flow than my normal period, and doesn't stop at night like my normal period does. I have missed two pills in a row before but my period has never passed five days long. Is this normal?