Pregnancy

Hey all! So I've been on the rod for two months. My boyfriend and I have unprotected sex. Since the rod my periods have been irrational, I bled for 4 weeks straight and this week all the bleeding has stopped. I'm constantly worried I'm pregnant. I'm 12 days late on my period however I took a preg test a few days ago and it says "not pregnant" .. I know with the rod you it totally messes with your period :/ tell me your thoughts?