I took the depo shot in November but then recently switched to cyclafem a form of the birth control pill in February during taking it the first month I was late for one of my pills and took it 6 hours late after that I waited a little over 2 weeks until had sex and he used a condom I got my period a couple days later but it was extremely short, now a month later in march I am on my second day of placebo pills and have no gotten my period yet and I've been having headaches for about 2 week, is there a chance I could be pregnant?