Glow keeps changing my ovulation date...

Courtney • 37 years old, married with stepkids. BFP with 🌈 after first IUI and due October 2017!
I haven't taken any Opk's but this week was supposed to be my fertile window. The percentages haven't changed and were the highest on Thursday and have continued to decline since... This is the last day of the window. BUT... For the last three days I have gotten notification that this is the most important day to BD. confused. Has this happened to anyone!