It is great that you are concerned about building healthy bones and at age 14, it is definitely not too late to start making sure you are getting enough calcium every day. From the time you are about 11 until you reach 24, you need about 1,300 milligrams (mg) of calcium every day to help your bones grow strong. While a lot of people drink milk to get this calcium, there is no reason why you cannot use other dairy products, like cheese or yogurt, or things like calcium-fortified orange juice or cereal to get enough of this important mineral. In general, the amount of calcium required means you need at least 4.5 servings of calcium-rich products daily. A 6 oz. serving of yogurt will provide between 20-30% of the daily value for Calcium (the daily value is based on 1000mg for Calcium), even though teens need about 1300mg. of Calcium daily. This means that a 6 oz. serving is providing between 200-300mg. of Calcium. One 8oz. glass of milk provides about 300 mg. of Calcium. Cheese: a 1" cube, which equals about 1 oz., provides approx. 200mg of calcium. Some "Rules of Thumb" that apply (no pun intended) include the size of your thumb or 3-4 stacked dice as an equal of an ounce of cheese. If you prefer sliced cheese, then approximately 1 slice of cheese would equal one once. Other foods should tell you how much calcium they have in them on the side of the package.
Adolescent bodies have a higher capacity to absorb and retain calcium than adult bodies do, which makes them especially efficient at bone building. But remember that bone also needs vitamin D to move calcium from the intestine to the bloodstream and into bone. It is important that you make sure you are getting enough of this vitamin (which you can get from being out in the sun or from various food products, including cheese, fish and certain cereals) to let your body use the calcium you are eating effectively.