Irregular periods after regular cycles

I got my period at 8 weeks postpartum 😩 while exclusively breastfeeding. Baby is now 7 months, we have introduced solids (he doesn’t really eat much) and he is still breastfeeding. My period has been regular since (like on the dot).

But I noticed I was 3 days late last month and when it came I bled 2-3 extra days. This month I’m 5 days late,, I am almost completely sure I’m not pregnant and have been having pms symptoms. Can it happen to have irregular cycles while breastfeeding after being regular?