CD19 and no positive OPK yet

Amanda 🐼 • With my husband for 19 years, married 10 💍 Postpartum RN 💉 Addison Sarah born 1/1/16 🎀 Baby #2 due April 2019 🤰Obsessed with Glow 🤷‍♀️
CD 19 today. Still haven't gotten a positive OPK. These are from last 3 days. Have all been just super light. Pic is bad quality but they're all about the same. Previous days the same. Been testing since CD 14. Last cycle was positive on CD 19, but previous to that was around 15 and 16. What's going on?? Making me nervous!