I'm not sure..

The past two months my period has came on the 4th before I got pregnant they were irregular the longest in between periods was 30 days shortest was 26 days I know having a baby changes everything I'm also breastfeeding but I was wondering what's the longest you can go in between periods before you get it sorry if this doesn't make much sense I'm just worried and confused because my baby is 5 months old and I'm scared to be pregnant again we were so careful too.