Birth control

I have been on the microgestin birth control for a few years now. Ever since I started taking them, my periods have stopped. I haven't had one in idk how long. The only way I start a period is if I forget to take a pill. Or take it too late. Each year I ask my doctor if this is a normal effect, she says yes. That it's completely fine. I can't help but feel nervous that this is affecting my fertility for the future. Has anyone else used this form of birth control and had the same outcome?