I honestly think genetics play a big role. I've had the opposite experience, particularly with my first, who was supplemented her first year with bottles due to extenuating circumstances. She also flat refused to co-sleep (she would cry in our bed until we laid her in her own cot, then she'd snuggle down and go right off to sleep). I was also experiencing severe ppd after her birth which led to most of the bottles she got being given by dh in the night to lessen the impact of sleep deprivation on my ppd, so not an awful lot of night nursing. In spite of all that, my period did not return until 11 months pp. I can no more take "credit" for that than you can take "blame" for yours returning so soon.
The rest of my kids were EBF and extended BF and all co-slept, but they all started solids at 5-6 months (by their choice, helping themselves to my plate) and the return of my period ranged from 14 months pp up to 22 months pp. It's nice having a long break from AF but, for me, it's a double-edged sword because, until my period returns, there is simply no budging the weight which I gain with BF (never have any leftover pregnancy weight, I gain it all while BF!). So, I end up looking forward to AF's return so that I can finally ditch the extra weight!
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