Is it normal to be on bc and get mild period cramps about a week before your period is due? i take bc correctly and almost always use a backup method

Mittelschmerz: Perhaps you're describing mittelschmerz (http://www.mayoclinic.org/diseases-conditions/mittelschmerz/basics/definition/CON-20025507) or middle pain which is ovulatory discomfort about 2 weeks before menses. Endometriosis could also make menses painful. Check w/your family doc for options eg changing birth control pills to schedule menses quarterly or even annually in order to minimize this pain.