So confused

Kaetlyn

So I started bleeding today, after pink spotting yesterday. It was heavy but now not.

I assumed AF but my fertility doctor said 2 weeks ago, I hadn’t even ovulated yet, so my bleeding doesn’t seem consistent with it being a period but possible implantation or breakthrough…

Has anyone experienced similar? I’m not showing signs of period outside the bleeding. My lining was 20mm thick on the 17th.