When measuring your waist, you are supposed to measure at the slimmest part of your waist. For me, that is way up above my belly button.
Schmoodle - the pants your daughter is talking about used to be called "hip huggers" for a reason! They rest on your hips not at your waist
Edit to add - as far as those charts go, do they say which part of your waist to measure? You could always call the company and ask.