Joanna, it's not so terrible, that you think. You will slim, but to become slim, you must do sport. If you do gymnastics, you will be slimer, than before. Don't be shy, because it's not ugly. When someone laugh at you, you mustn't pay attention for them, they don't understand anything. So, if you want to be slim, you must to do something, because in you ages it will be not so difficult. Good luck!