4th day late

Usually I have my period every 28 days and it's now been a week past that. I've taken 2 tests and both came back negative. I have no symptoms of a period usually my boobs get a little tender ,but not much else. My lower back has been cramping. It's really hard to get an appointment with my doctor. I need some answers please help. I'm never this late. Also I've been getting the same discharge as if I was ovulating.