My periods are very irregular when I am not using the birth control pill, as I have PCOS. My period is about 6 weeks late now. I have taken 9 pregnancy tests , all negative. I m wondering if my medicine (Vyvance, Pristiq , Lithium , Klonopin , Xanax), the high stress I have been going through. Poor eating habits, and increased alcohol consumption can be the cause of the missed period, or should I continue to worry about a pregnancy?