I am a thirteen-year-old girl and am around 5'10. i weigh 160 pounds. should i lose any weight? and how?

my friends tell my im skinny since being quite tall doesn't really show the fat. twice a week i do intense pilates and i don't eat a lot and i can't seem to lose weight. i live in a country where the gym isn't really available. i do go play tennis occasionally. I NEED HELP!