Super faint to super dark OPKs

I had a D&C in December and I know it can change things up from how they were. Prior I would get dark (not positive) OPKs consistently while testing right up until the positive. Now they are all super super faint. My question is have yours been super faint one time and the next,bam, you get that dark positive? It's my first cycle tracking with them since Sep and just curious to others experiences