How much should a thirteen year old way if your height is 5feet and 8 inches?

A lot of it depends on what type of body you have. Muscle weighs more than fat and if you are naturally busty, breasts add weight too. I'm 5'8 and range between 112 and 125. I'm naturally thin with long muscles and I tend to look best around 115 however, I also have very narrow hips and small wrists. It shouldn't really be how much you weigh (you've heard of skinny-fat? When you can be skinny, but look doughy) it should be how you look in the mirror.