Is there any reason, any event to make you feel this way? (You don't have to answer me, just ask yourself the question.)

Some people indeed do feel they're going to die before the death comes, but they are mostly very old people or seriously ill. They are mostly at peace with the knowledge of their shortening days, not paralyzed by it.

If your panic attacks do not have any apparent cause, you should consult a mental health professional. Maybe they can help you find a way how to stop your brain from convincing you that you are going to die soon, because that is not true. I am sure you can change things for the better.