Should i go on a diet, how much should i eat?

Well i have this weird question... im 15 years old, means, im still growing. i have this weird habit - counting my daily calories. i eat like 600-800 a day or less. now, i dont get it... to keep my weight or get lose a bit, how much should a teenager like me eat?[THATS THE QUESTION!] i weight about 47 [or 2 kgs less] kg's and height 1.66+cm. i am slim relatively, i suppose. i dont eat any sweets or chocolate but i actually miss eating chocolate and ice cream :( i actually ate some lately.. but a small amount of portion. please, help me to solve my problem, thank you.