I exclusively demand bf Spock, who never went longer than 3hrs between feeds, i got af back straight away, like clockwork never missed a beat. Im not 100% sure i was furtile though, as we have male factor and cant fall pg naturally so i never actually used contraception or paid close attention cause falling again wasnt a stress we had. When Spock was 1 i had a trial cycle to see if i was ovulating and it said i wasnt.
But it is entirely possible i know a number of women who have fallen with a bub under 3months. If your unsure and dont want to take the ridk, use condoms, and discuss with your gp about sutible contraception