No period

Hi, today I am 19 days late according to Glow. Tested upt when I was 3 days late but got BFN. Suffering from a mild cramp and feel slightly different with my menstrual cramp. Feeling nausea on and off especially after taking any food. I have experienced with brown spotting a week before my expected period. Have any one here experiencing it too before? When is the right time to test the upt? Thanks in advance