I'm 5foot 2 13 year old girl how much should I weight?

Depends on maturity. and level of muscularity. Most ideal weight for girls your age who are 5"2" and have already started menses would be 110 to 120 pounds, but if you are very muscular, you could weigh more and be healthy or if you are slow to development, weigh less. Eating a healthy diet, getting lots of rest, exercising regularly are the most important things at your age.