Your doctor is totally out of date, awful to have to say that when she should know better. Use as much as needed to relieve your symptoms and to stop you from getting to the chronic stage of this disgusting condition. When you feel you can reduce your dose then so be it.
My treatment is daily, Vagifem and Estriol cream, with the blessing of a gynaecologist and my now new surgery who have been amazing and so up to date on topical HRT.