This is called stress incontinence and you are certainly not alone experiencing this.  Studies have reported a significant number of teenage girls have occasional urine leakage, some to a greater degree than others.  If you lose bladder control when laughing then chances are you can also lose bladder control while running and jumping.  This is usually do to weak pelvic floor muscles.

There are very good results with strengthening these muscles.  Please read through my blog where I give specific exercises that can help you on your way to better bladder control.  Great that you get this information now as the incidence of stress incontinence typically increases with age.  You will be a step ahead of the curve when you reach your child bearing years!

Tasha Mulligan