Most likely you & baby are doing just fine. After 6 weeks or so SOME babies (not all) switch to a less frequent poop pattern, and it is perfectly normal. Some go several days-even a week or more-without a poop. These babies are not constipated, and they are getting plenty of milk. They just don't need to poop as often as before. Breastmilk is an extremely efficient food.
Of course for the mom concerned about intake, this turn of events can be alarming, but barring any known difficulties, your milk supply should be well established by now. Just keep nursing baby with the frequency you both prefer. All should be fine.