Debbie,
Mild, moderate and severe are relative to what one is taking into consideration. Your doc may be considering a comparison to someone who has what he perceives to be severe disease, while you on the other hand may be considering the level of life-style impact that your symptoms have on you & your life.
You might ask him "Very mild disease compared to what?" or "On what do you base that assertion?"
Its like when advertisements say things like "Our tires stop on ice better." Better than what? A ski?
With love, Erika