Very Unusual Cycle

blood

SOOO the highlighted part would be the week where I would’ve “conceived”. My period has been missed and currently on cycle day 51. I took a pregnancy test on 01/21, 01/24, and this morning. All three tests turned out negative. So why hasn’t my period come yet? (((I’m currently no longer on BC but have been taking plan b’s as my EC.))) What could be the issue ?