Does breastfed delay period?

It should have started a week ago but no sign of aunt flow. I'm feeding Baby on demand. Does that affect things? I believe my cycle came back after delivery but it's all so blurry. I definitely was bleeding but I don't know when the postpartum stopped and when an actual period began. I started the mini pill around 8 wks postpartum and it made me bleed every other week so I stopped taking it. Now, no bleeding or sign of a period. I took a test a couple days ago and it was negative.