DID I OVULATE?

Shelly

My first time using these opks. I know you’re supposed to look out for a test line that’s darker or as dark as the control line which looks like it happened on CD15. My lines have stayed consistently dark since then. On CD18 it got a little lighter and then CD19 was pretty strong again. Is this normal? Should they be getting much lighter since CD15 was my surge? Please let me know what you think. I’m so confused!