After my first I had a period (five days of heavy bleeding, cramping, looked just like a period) 9 weeks postpartum (two weeks after I stopped bleeding).
My midwife told me to 'wait and see', if it returned the next month it was a period, and if not it was a "return of postpartum bleeding".
It wasn't a period.
After my second I had a period (five days of heavy bleeding, cramping, looked just like a period) 7 weeks postpartum, about two weeks after I stopped bleeding.
But I wasn't breastfeeding, so I waited for it to come back.
And waited, and waited... and it turned out it also wasn't a period - I had conceived just prior to it and I honestly have no idea what that bleeding was!