Positive OPK before period starts

Sidra • 👼🏼 9-18-17 ❤️ 👼11-17-18 🙏🏽 Praying for our 🌈👶🏼❤️

I ovulated on the 1st or second of April and had an <a href="https://glowing.com/glow-fertility-program">IUI</a> done on the first. I took ovulation tests all month. Watch them get darker until I peaked (on the first and second) and then go completely light (4 days ago). I went ahead and kept taking them and now they are dark again like I'm peaking. Anyone know why or what it means? Any one had that happen with these tests? AF not due the 15th.💖🍍