On CD16 I got the closest to a positive OPK I’ve ever had. (See pic)

Because of that I kept testing (three times a day!!) but they have just got lighter and lighter. I tested the evening before (CD15) and it was lighter than the test above but getting darker. I’m now CD18 and it is clear negatives - barely a second line.

Have I just missed my surge? Glow keeps moving my ovulation date but I don’t want to keep testing and wasting the strips. Opinions please :)