Breasts are mostly a combination of fatty and glandular tissues, and either of those parts can continue to grow at any point in your life, depending upon the influences or stimuli that they receive. This could be a normal thing based upon what's going on in your life at the moment, or it could be an indication of something that needs to be looked into. For instance, if you begin to gain some weight, and your fatty tissues increase, the breasts would be expected to increase in size too. Sometimes, probably for mostly genetic reasons, a woman's breasts may be a bit more sensitive than other areas to weight gain like this, and they can begin to increase before other body areas. The glandular tissues are mostly sensitive to hormonal influences, and things like fluctuations in your own body's hormone levels, such as might still be happening in a young lady your age, or any outside hormones you may be using like birth control or dietary supplements that might behave like estrogen or stimulate estrogen production in your body, may cause an increase in the size of your breasts. If you are sexually active, another thing that needs to be considered is pregnancy, as some enlargement of the breasts can sometimes be one of the earliest indications of this. Also, there are some unusual hormone factors too, like benign growths in the pituitary gland which can stimulate breast growth and milk production, and this can cause an increase in breast size too. This one usually also causes some milk production, so one may also notice some leakage from the nipple or staining of the bra. If you are experiencing any pain or tenderness of the breasts, or if you think that the breasts are enlarging irregularly - one breast larger than the other, or one breast larger in one area than the other - or, if you feel any lumps or masses in the breasts, it is very important to have your doctor examine your breasts. Also, if you notice any other associated findings, like changes in your mood, your menstrual cycle, energy level, or any other sensations that just don't seem "normal" to you, it is always best to err on the side of safety and just have your doctor check you out. I hope this helps. Good luck!