Period changes after pregnancy

Mel

I gave birth sept 1/2021 , I used to always get my period around 30-33 days and every month

I do breastfeed still but I’ve been noticing my period cycles are 1.5 months later or even more ever since

Example last period was may 28 and it’s July 14 and I still haven’t gotten it

Should I be worried? I took a test and it was negative

When did your period regulate after birth