What Causes Delayed Period While On Lisinopril For Hypertension?

I am currently taking 10mg of Lisinopril for my hypertension. I have kidney scarring from surgery that has raised my blood pressure. Usually, my menstrual cycles last 36 or so days. Currently, it has been 44 days and I don t know whether it is an effect of my medicine or me being pregnant. I m not sure about the pregnant thing, but I recently did anal with my boyfriend and I think his semen dripped down to my vagina. I don t know what to do. Please help me. I m also 18.