Hi everyone!

So my boyfriend and I are trying to conceive #1. I am so confused on how the ovulation strips works. According to the app and my bbt, I ovulated yesterday. On that day, my ovulation test was positive aswell. Of course, we bd BUT should I have not bd the day before ovulation? If so, how does the strips actually work? I feel like I missed out on a potential day! (An other app suggested that I ovulated couple days ago so it got me also confused!)