Hello,I am 13 years old and will turn 14 in August I weigh 10 and a half stone I don't think I am very skinny but however, I am not fat either. As I am 10 and a half stone am I overweight for an average 13 year old???

Your height would come into this sort of calculation.  If you're happy with your weight then don't get obsessed with it, often directing focus elsewhere such as doing well at school will help.  You don't want to be one of the thousands of people spending their life obsessed with diets and weight, stay healthy, acknowledge how you feel (some people confuse feelings with hunger, or eat when bored), have fun and do your best in school :)

You are fine. Enjoy your youth. Society puts soo much pressure on teens to be thin. The most important thing is health. If you need to lose weight because of health reasons then by all means do it. But don't put to much anxiety on yourself it could lead to other insecurities