Hi C.,
I know that my cycle was all out of whack after having my son. I had some pretty bad oversupply problems with breastfeeding, and in trying to work that out, my period resumed only 6 weeks after having my son. I had an IUD put in place when he was 8 weeks. After that, my periods were very inconsistent- sometimes I would skip months while still breastfeeding, sometimes I would have my period twice in a month. I completely stopped breastfeeding when he was around 5 mos. and I still have irregular periods over a year later! You can probably expect your cycle to be all out of whack for a while, but unless you are using a very effective BC method (like the pill or IUD), you might want to take a pregnancy test to be sure. I know I took several tests because things were so unpredictable (even though I had an IUD).