Oh, the zoo sounds fun! One day will not affect your supply. Consistent change in demand will lower the supply, but not just one day.
Follow up with other questions :)
In a situation like you faced yesterday, I probably would just have offered her the food, knowing that in most circumstances, you'd nurse before giving solids.
Yea, I kept wondering if there was a nursing room anywhere, but then I never went to go find out because we were so busy (I have a 2 yr old also!).