One thing to keep in mind about causes of a delay in stooling.  Feces are
composed of a large number of dead cells from the lining of the gut.  The
cells of the gut turn over at a very rapid rate and therefore dead cells are
sloughed continually.  These cells compose a good deal of the bulk of the
stool. So even if all of the brestmilk were utilized there would still be
these cells contributing to the stool.

My first child went once a week for a few months and when he did the stool was
quite copious. But is was still the semisolid, mustardy stool it had been when
he went everyday.  Just more of it.

Mardrey Swenson