Glow prediction

So usually Glow is exactly right or a day off on predicting my periods. I was supposed to start on Monday but no sign of Aunt Flo. I spotted last Friday but that was it. I took a pregnancy test and it’s negative.

Anyone else having any issues?

I only use Glow to predict my periods because after 6 years of TTC I’ve come to the conclusion that when God thinks we’re ready for another baby then we will be blessed! TIA!