I share your nervousness of the dentist, even if can only envy your cavity-free existence.
My dad has never been one to let frailty of any sort stand in his way and is also not so great at subtlety or using only a minimal amount of force. Pain, in his book, is something to be ignored as you continue towards your goal.
Consequently, his dentist told him to stop flossing because he was doing damage to his gums on a daily basis. So, there's at least one person in the world who has been told by his dentist not to floss.