If you don't believe in Church teachings, then, for all practical purposes, you are no longer a Catholic. Of course, you would always be welcome to return.
In fact, if your lack of belief has come about through no fault of your own, then your act of material separation from the Church would not even be considered sinful. That's between you and God.
If you have any interest in the Church at all, it would be worth your investigating Catholic Answers. Most people leave the Church without fully understanding the reasons for the Church's teachings. Let's face it. A lot of us were very poorly catechized.
Nope. I want a formal “You’re no longer welcome here” from somebody official...