hi jespehine! congratulations to you on your wonderful new baby and on your successful nursing!
Your baby is probably fine; pooping can be very erratic in newborns. breastfeeders especially tend to use up all thier food, it's the most efficient food there is, and leaves little to poop out. if you are really worried you could try giving the baby a bit of tepid prune juice w an eye dropper or on your finger, it certainly won't harm him if given a teaspoon or so at a time, but not more.
try to avoid formula if at all possible, it really is a poor food substitute, no matter what the doctor may say (remember that they get money and perks from formula companies.) how about trying a pump, the best is the Medela Hospital Grade Classic which you can rent from any surgical supply store and should come w very clear assembly directions (husbands are good at putting these things together.) it will be a bit of money to rent but your breast milk in a bottle, if you can't be with the baby, is so much better than any formula, it is really worth it.
if you continue to have concerns look up your local La Leche League chapter on the web and call the chapter leader or try a meeting, they are really the best nutrition and nursing resource at this early stage for you.
if you would like to chat more about nursing you can email me directly.
good luck and big hugs!
J.