Spotting during fertile window

The second day of my fertile window, I spotted. I read online it can be a sign of ovulation but after three days of ovulation tests all coming up negative, I'm not sure. Been off birth control for over a year but only been actively TTC for a couple months. Anyone else experience random spotting during fertile week? Have any ideas what it could be? Maybe I'm looking too far into it and it's nothing, just thought I'd see opinions!