Have you read the book "Taking Charge Of Your Fertility"? By Toni Weschler.

It is just brilliant, I was charting while breastfeeding, it is a bit tricky, but kind of do-able, and you still do get more of a clue as to when you are ovulating than just guesswork.

You certainly can and often do ovulate before your first period post partum.

All the best with ttc