seawitch, it is not being postpartum that spaces babies. It is exclusive breastfeeding. If you were unable to breastfeed, you would expect your fertility to return pretty much immediately, just as you experienced.
OP, with ecological breastfeeding, the chances of pregnancy before 3 months (before any post-day 56 bleeding) is pretty close to 0, and the chance of pregnancy between 3 and 6 months (again, before any bleeding after 56 days postpartum) is about 1%. This bleeding that you are experiencing is likely some sort of hormonal bleed, but it is very unlikely that you have already ovulated and are pregnant. It is possible, but not certain, that it is related to your fertility trying to return. However, because you have experienced bleeding after 56 days, you no longer qualify for LAM and need to choose another way of postponing pregnancy (or not if you want to get pregnant again soon!) from here on out.
If you experience 6 weeks with no bleeding and no fertility signs, Sheila Kippley (ecological breastfeeding) says that you can consider yourself to be in amenorrhea for ecological breastfeeding purposes (I had a day of spotting about 4 months and then nothing until another day of spotting around 20 months and my first period at 21 months with ecological breastfeeding), but the effectiveness of relying on breastfeeding alone after post-day 56 bleeding is significantly reduced, so I would be much more careful about not ignoring fertility signs. I would definitely keep track of CM, and I would temp for at least 6 weeks after any bleeding or any patch of more-fertile mucus that lasts more than a day or 2.
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