Just adding my experiences with delayed menses during breastfeeding.  My periods
never have been regular.
#1, nursed every 3 hours around the clock, solids at 4 months (did not sleep in
my bed)  menses at 10 months
#2, nursed "on request", solids at 10 months,(slept in my bed) menses at 16
months
#3, nursed "on request", solids at 6 months, (slept in my bed) menses at 18
months
#4, nursed "on request", solids at 6 months, (slept in my bed) menses at 14
months
Everyone is different!
Susan