Not pregnant right?

First time posting but have been reading for a few months! Been trying for half a year, and am 3 days late. I used a Clearblue test yesterday afternoon and then a Wondfo strip first thing this morning. Both are clearly negative, not even a faint line or indent. I probably just have a missed period right? It’s only happened to me once before ten years ago when I was not sleeping much and traveling.

Other factor could be that my normally regular 28 day cycle increased to 31 days the past few cycles (probably due to a low carb diet that I’m doing because of prediabetes). My OPKs using the pee strips (Clearblue said I was peaking at the expected times though)

didn’t really show a surge or peak during these cycles too. Thoughts? Do I keep testing?