1st period postpartum

After I gave birth to my daughter, my OBGYN started me on OrthoMicroNor for birth control since I am breastfeeding. My daughter just turned 12 months old on 12/10/2021 and we are still breastfeeding (yes she does eat actual food and recently we introduced whole milk occasionally). My period returned this week for the first time since before I got pregnant. I vaguely remember something about my doctor mentioning that I should notify the office when my period returns because of being on the mini pill but that was over about a year ago. Has anyone else heard this?