The instructions say: If you miss 3 or more "active" [white] pills in a row (during the first 3 weeks):

Sunday starter-- Keep taking one pill every day until Sunday. On Sunday, Throw out the rest of the pack and start a new pack of pills on the same day.

You may become pregnant if you have sex in the 7 DAYS after you miss pills. You must use another birth control method as back-up for those 7 days.

Now, the woman at my doctor's office said I should basically start over and use back-up protection for the next 3 weeks to be safe. Why should I not trust the pill instructions?