Will retest tomorrow

I’m currently on the injection and started bleeding heavily around 4 weeks after getting my first one but stopped bleeding around 5 weeks after that. Could have been to do with postpartum bleeding as I have a 4 month old. I’m on the injection because I want my next pregnancy to be healthy for me and baby but I want another baby so much, so either way this goes I will be ok with the result. Just wanted some opinions on whether this is + or - and some stories of getting pregnant on the injection