Hi welcome to DWD, I was on and off Sertraline for a a good few years before I went on to it permanently been on it for about 25 years now.

I agree with what Paula, Arty and Suzi have said, make an appointment with your GP and explain how you feel, then discuss the options. From my own personal experience repeatedly stopping and starting medication isn't a good thing as modern antidepressants are very slow acting typically 1 to 2 months and from my experience even longer before you get the full benefit.