Advice 🤔

Tj <3 • 23// England// 26-07-18 👼🏻18-09-18 👼🏻4-1-19👼🏻 Elsie 💕 07/03/2020 19-8-22 👼🏻 Baby boy 💙 - due may

I was told by my Dr to mark the 1st day I started bleeding as CD1, it’s now saying I’m 3days late today, I’ve been trying to track ovulation since 3rd of feb and they have ALL been negative. Is it possible that I ddI ovulate on the 1st? I can’t see how that’s possible