DID I OVULATE?

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 I think happened on CD15 but my lines have stayed consistently positive I’d say since then. CD18 started to get a little lighter but yesterday CD19 was pretty strong again. Is this normal? Did my body fail to ovulate and is attempting again? I’ve heard this happens to some. Please let me know what you think. I’m so confused!!