Mine took about a year to settle down after DC2. Had a difficult birth with DC2 resulting in a lot of blood loss and then had 2 PPHs which resulted in a D&C. BF for a year and started with a light period after about 11mths. I then have over a year of never really knowing when my period was going to appear. Some months were really light others normal and they came at any point between 22 and 30 days (26 is usual for me). I went to see my GP wondering if it was age realted (42) but she said my body had been though so much trauma and then with feeding for a year it waqs just taking time to settle down. She was right they have settled down but it did take a long time.
having charted and ttc for 2.5yrs while feeding ds1, I noticed that if he fed a lot more, then ovulation was delayed - sometimes by as much as a week. This in turn delays menstruation, so it could be that.