5'7 and 120 -124 lbs 17 years old, runner?

I'm 17 years old, i think im about 5'7 and i weigh like 123 lbs, but it fluctuates from 120 to 124. I'm a distance runner and i feel like the only good ones are like 100 pounds haha. im not super skinny right now, my back is boney but my thighs are huge. how do you think my weight is? ideal for a distance runner?