Yes, purging twice a week will likely kill you within a few decades if you keep it up through the serious health issues you'll face from purging. That's assuming you maintain control of your ability to choose to purge. If you loose the ability to retain food in the stomach you will degenerate very quickly.
Yes this is an eating disorder. This is Bulimia. It can also do the same things to your intestinal tract that it does to your teeth and worse still it creates imbalances in your body that cause a domino effect of health problems over time. Worse for you, since you're in puberty and relying on balanced health to grow into a functional adult. The longer you engage in purging during these years of your life the more and more severe health complications you will have to endure through your life.
You need help. Stopping is not enough. You need medical evaluation to see if serious damage has been done and you need psychological evaluation to help you from falling back into this behavior. You need to tell your parents that you have an eating disorder and you need to get professional help.