You are 18, and you want to grow 5CM a year. Unless your family genetic factors are very good, it is unlikely. As for being as thin as 52KG, it's ok. You can choose to skip rope every day as exercise. Skipping rope 1 hour is equivalent to jogging for 3 hours, which can consume considerable energy. It is a very good exercise to lose weight. Jump for half an hour every morning and evening, and you can start exercising from 10 minutes at a time. It is not advisable to jump for too long at first, and then it can be gradually increased.