To put it into perspective I’m a 5 foot 4 19 year old who eats healthy and works out most days doing a lot of cardio, I’m about 8 stone 9. I have a fast metabolism and do not have big boobs by any means. Not to say that you are unhealthy because I am not in the position or have the scientific knowledge to suggest so, however as a growing teenager your calorie intake should be around 2500 per day. You need these calories in order to grow. I wouldn’t worry however I would definitely analyse your intake and find advice about overall physical well-being. It is a process that needs to be taken in stride, do not feel like you need to flip your lifestyle over night, but try to gradually alter your lifestyle and intake.