Welcome to HCM,
You have not mentioned that after your delivery did you start your period or not.
Due to breastfeeding
one might not get period many a time.
I think due to this you might not get period or irregular period.
So it does not mean there is effect on your fertility
Mind well that unprotected sex is not always safe during this period as any time ovulation can occur and one can be pregnant.
Ok and bye.