I'm not an expert on this topic since I was not able to feed like I'd liked with my daughter but I had every intention and desire so... Remember what you eat is what that sweet baby eats, therefore, things that might stop anyone up like cheese could be the culpret. If you eat lots of fruits and drink lots of apple juice and things that would normally help a baby poop, maybe that would help here.
As always consult your doctor, they will know best! If you think the baby needs to poop and can't, there's tons of ways to help with that! Ask the doctor if you can give the baby juice yet. It might be way too early but ask. If so, you might have to try several different types (each baby is different in what/how different things effect their bodies) but... Apple, grape, prune, juices tend to help them be able to poop. My daughter is a poop once a day gal and always has been. So when she hadn't pooped in a day I (even still) have to load up on fruits and juice to help.
The not so fun option if she needs to poop is a... (can't remember the name right now) its a wax little cone that you are able to insert and if need be, hold it in their bum. It does not hurt them at all, it may feel uncomfortable for them, and you will hate doing it but it allows them to push better. Typically the baby will poop as soon as you insert it. But it is a harmless wax that if nothing else will disolve and go away on its own.
Hope that helps, I know its not a technical or professional info but... :o) ~T.~