How can I tell when I've been ovulating when my period is irregular?

Very long story but basically today I found out that instead of taking the combination pill I have been on the mini-pill, which you're supposed to always take the same time each day. So I might be in deep 💩 Last Friday I forgot to take it in the morning and didn't take it till like 9 hours later 🙊 my pamphlet said "if you had sex within 48 hours of missing your pill, seek emergency contraception" weeellll we had sex 4 times that weekend. And it's too late for Plan B now. So what I'm wondering is how can I figure out my fertile window when my periods have been super irregular? Sometimes I can't tell if I'm just spotting, because I'll bleed very very light for like a day and a half. Or sometimes just a day. Sometimes I'll bleed for like 3 days. I keep track of everything on a pregnancy app but even that has no idea what to predict what's going on 😂