Why is it so that when people try to quit taking antidepressant ( quit, under the observation with doctor) that you get a lot of anxiety symptoms?

Discontinuation: Stopping antidepressants may lead to discontinuation symptoms, including anxiety -- even when done gradually under doctor's supervision. In that case, the tapering process needs to slow down. Another possibility is recurrence of the symptoms for which the medication was originally prescribed. It can be hard to tell these apart sometimes. I'm glad you're working with your doctor on this.