To be or not to be

I bought a DIY test kit and tested 1 day earlier before my app said that my menses would be due ,results neg. I went to the doc cos of sorethroat but went for a urine test cos menses according to my app was 1 day late, results neg. Have been feeling nausea. Menses for past months fall on either 17th or 18th, till now menses not here yet. Chances ?