I cant help wetting my self when i laugh?

I am 14 years old, ever since i can remember i have had problems holding my bladder. It has haunted my past. it doesn't happen too often but when i laugh strongly i cant hold my bladder any more. My parents thought it was something i would grow out of but clearly i haven't. Im going to go to the doctors soon but i am very embarrassed. I feel like crying when it happens, it hasn't happened in front of friends yet but i know if i don't seek help this problem will soon occur, and i know from the past how embarrassing this will be. If it happens at home i spend most of the day hiding it or a change of clothes because im too "hot" or "cold". I do not wet the bed but i think of myself as an embarrassment towards my family. As my older sisters friends have a glimmer of what occurs when i laugh too much. please help me :/ x