After my first I started having mostly regular periods (while nursing, starting when he was about 8 or 9 months old). They got really heavy and I had a few back-to-back ones after he weaned (around a year) and I switched to combination pills instead of mini-pills. After the second period with one weeks' break we decided we would just stop pills and see when I got pregnant (I didn't have another period).
After my second, I got my period around a year and started regular pills when he weaned (after 13 months). My bleeding was all over the place--it would last at least a week at a time, never regular, sometimes 6 weeks without anything then two weeks of heavy bleeding. It went on like that and weirder for at least six months and I tried different pills but by then we wanted another baby so I just stopped. Never got regular. Before kids I was completely regular. It will be interesting to see what happens when I wean number 3. I know a lot of moms who have really regular cycles right after weaning kids, so hopefully you will too. :)