Prolonged bleeding

So just started birth control for the first time and I am 20 years old idk if that makes any difference. I started taking it mid-cycle because I had mistaken spotting for my period. (You’re encouraged to start birth control the first day of your first period when you first start it.) I started my period before the placebo pills. I am on the placebo pills now but I have been on my period for 13 days with mild cramping. This is not normal for me because my periods usually end in 7 days. Could this prolonged bleeding be a side effect of starting new birth control at the wrong time and should I call my doctor? I just had a check up with my OB/GYN less than a month ago and she said everything looked great. I take Junel Fe.