I am 19 and my period has been consistent all my life. I began taking birth control 3 or 4 months ago maybe, with no change to my cycle. However my last three periods have been a week early even though I'm consistently taking my pills. Any ideas why this could be and how to get it back on track? It's not fun having it this often... This is a pic of what my cycles have been, and you can see today's date right on the bottom