Faint positive yesterday, but got period today

Hi, has been 3 months ttc. I usually have regular periods and a good cycle. My period was delayed by 3 days, tested for pregnancy yesterday, it was faint positive. But got my menses today. Yes, its my usual period and not implantation i guess. Feels like normal AF, heavy bleeding than usual. Can someone tell me what happened! I just cant understand why:( Thank u for your time and help!