Hi! The other two are right, your fertility is wonky due to mixed up hormones after birth, especially while breastfeeding. Were you supplementing (with formula?) or pumping more often then nursing? That can cause you to start early, especially if you are doing that and then go back to nursing. I think with my third when I had to give her formula (she had no poopy diapers for several days, and she was a newborn) my period started quickly. But then I was able to phase out the bottles and nurse exclusively and my period stayed away until she was 11 months old. :) I got pregnant two months later.
As far as child spacing is concerned, my oldest was 5 months old when I got pregnant with #2 and me second was 6 months old when I was pregnant with #3. But I was bottle feeding. One year apart was fun, I enjoyed it. The next two are 23 months apart and I breastfed exclusively to 6 months, nursed to 13 months.
S., mom to 5 and lovein it!