A.C.
Wow...in this day and age, with everything we know about breastfeeding, the response from the nurse surprises me. Are you sure she understood that you are exclusively breastfeeding? Or did you assume that she looked at your chart?
It is SO completely normal for an exclusively breastfed baby to go 7-10 days without a bowel movement. As you've said...she is wetting plenty of diapers, not uncomfortable, and stomach isn't rigid...all points to no problems. If it goes longer than 10 days I would only be concerned that she isn't getting enough hindmilk (that is where a lot of the calories from fat come from).
Breastmilk has natural laxative properties...we've even given some of my frozen milk to my constipated formula-fed niece to get things moving and it worked like a charm.