OPK help please 😬

Here are 4 tests I took. From top to bottom is Saturday night, Sunday morning, Sunday night, and Monday morning. I thought I ovulated Saturday but then today(Monday) looks darker. I just don't understand why it would fade and then get darker. I will never use these blue dye ones again. Any insight or help would be appreciated thank you. I BDd Friday morning and Sunday morning so hopefully I'm good.