Natural child spacing

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Just curious if there is any mamas out there that has done natural child spacing via breastfeeding. I’m 4 months postpartum with my 2nd child no period still nursing day on demand and at night atleast once still. Just curious if it worked well for birth control for anyone with my first I nursed her for 17months and got pregnant with my second around 12months (we were trying) but this time just curious since my periods still haven’t returned (the first time it was back at 12 weeks with EBF) if im infertile at this time (which would be cool cause we don’t use other contraception at this time just pull out