OK don't be alarmed but FYI there was an infantino brand carrier-bag style sling that was recalled...gosh, a while ago. A couple of years maybe? Not a safe sling.Oh, I also have an Infantino carrier, but it's very difficult nursing in it.
as far as the poop goes, my bet is it's due to the formula. Even 5 ounces a day could make a difference...I mean, that is about 20% of your baby's total intake, right? It's going to have an effect.
If your baby is peeing normaly, shows no signs of illness, and not having any other signs of dehydration, that is most likely what it is. Formula does some funky things to poop and can cause constipation.
Here is something else that really worked for me as a new mom trying to cook (I was also learning to cook.) I bought a "five ingredients or less' cookbook. Guranteed very simple and usually fast recipes.