Opk’s

Hey ladies are there any of you out there that get really dark almost positive lines which then fade without getting positive? If so do you then get a positive in the next few days? A few days ago my lines got real dark but not positive and from then on they are just fading 😕 not sure if I’m even gonna ovulate! My app says I’m due to ovulate in 2 days so wondering whether other people experience this?