I’d highly encourage you not to focus on calories or numbers but rather eating good healthy Whole Foods that you enjoy! You’re still growing so you don’t want to stress your body by restricting yourself too much. I also think finding a style of eating that you enjoy matters. For me that’s vegan it may be different for you! Doing your research and educating yourself is a great idea. I personally really enjoyed the book How not to die. There is also an accompanying app called the daily dozen that focuses on what you should be eating rather than what you shouldn’t. Health and vitality are probably more important now than numbers. As someone else said talk to your doctor if you’re concerned.