Don't worry, stripes are just adipose tissue pulled by the rapid growth of the body, and have nothing to do with height. You are only 15 years old, and you are just beginning to grow up. Boys don't grow tall until they are 25 (some are 28). As the saying goes: twenty-three, run around. That's what it means. A small part of height depends on heredity, and most of it depends on acquired nutrition, exercise and so on. It is not difficult to grow taller as long as you eat more nutritious food and strengthen physical exercise.