Is this normal.

So me and my boyfriend have been trying this month, and keeping track with my ovulation. Well I have PCOS too so In the past it was hard to keep track withmy periods being crazy, well anyways I got a D&C 7 months ago and since then my periods have been normal and everything has been great. Well I was supposed to start my period yesterday and then 2 days before that I had bad back pain and pink spotting then it went to straight brown stuff/blackish... well fast forward to now a day late. 1 day late & there’s no spotting nor back pain and I’m getting negatives on pregnancy test, And I tested a couple days back and got a negative also. Does anyone know what could be going on? Could implantation bleeding occurred then and that’s why I’m not getting a positive yet? Please help lol 😭😂

(PICTURE FOR ATTENTION my beautiful babies❤️)