1st month of ttc, I’ve decided to use the opk for the whole month to see the trend. I have had a positive opk on the6th of December I believe I ovulated on the 8th. I have had some spotting on the 17th and I thought af was coming early. I carried on doing the opk and the line is getting progressively darker. It’s showing positive today. What is going on do opk show up positive before af? I’m due on the 28th.