Confused when to test bc of glow and cm

Usually af is regualar every 4 weeks which would make my next af to start 5/8 but for some reason last month i was a week late so now glow says af isnt due till 5/15 so im not sure when i should test.i thought about testing mothers day then if its negative test a week later because of glows information but not sure and also my cm for like the past 4 days has been eggwhite so if af due 5/8 could that mean i may have concieved or if af is due to show 5/15 possibly im ovulating