For most people, how tall they will be as an adult is defined well before they are teenagers--it's the result of genetics. If your parents were both short, you will probably also be somewhat vertically challenged. The onset of puberty also has an effect, because the earlier you enter puberty, the more time you will have to grow. But other factors, some of which are still at work during the teenage years, can affect height.
Grow taller though the teen years
Eat well. Diet influences every aspect of your health, including height. Making healthy choices with a balance of nutrients gives your body the energy it needs to grow. People who suffer from malnutrition, especially as children or older generations, tend to be shorter. Calcium and Vitamin D are crucial for your bones.
Exercise. Exercise keeps bones and muscles strong. People tend to start shrinking when they become middle-aged because of a loss of bone density and muscle strength. Weight-bearing exercises are particularly important for bone health.
See an endocrinologist. If you've stopped noticing growth rather suddenly, especially in the early teenage years, it may be the result of certain diseases. Talk to your regular doctor, who may refer you to a specialist. If you suffer from a disease of the glandular system, an endocrinologist can prescribe hormones to increase height and solve other medical issues you may have.
See a surgeon. One very drastic measure you can take is to undergo a surgery to break the bones in the legs, then wear braces to stretch the bones as they regrow. It is called cosmetic limb lengthening. While you can add up to 4 inches, it is a very painful major surgery and most surgeons will not perform it on teenagers.