Someone please give advice.

I am currently 13 weeks postpartum. At 8 weeks pp I had to have a d&c because I never stopped bleeding because of retained placenta after csection and a blood infection because it was untreated for so long. I still haven’t had my period, and am showing many signs of pregnancy that I had last time. Three days ago I had some light pink spotting and cramping(possibly implantation). I took a test that day and it came back negative (I took it late in the day and either way I wouldn’t be far along if I was)

My question is when do I take a test since I don’t know when my period is technically missed I had a tiny bit of light pink spotting again today.

Please let me know when you would take it! Last period was seriously November 22 of 2018 so I have no clue.