Breastfeeding and af

Has anyone started their period since having their baby and then suddenly stopped? Ive had 2 periods since giving birth 3/10 & 4/10. Its now 5/16 and no sign of a period. Ive taken 3 pregnancy test and all negative. I am ebf my son and have the paragard in so pregnancy is unlikely. I contacted my doctor and she said that irregular period are normal while breastfeeding. I just didnt think they would become irregular after getting 2 periods exactly a month apart, i thought that meant they were regulating after giving birth. Anyone going through or has gone through something like this? Did your period ever regulate while bf or not until you stopped? How long in between periods did you go after getting your intial pp period? Thanks!