Is this normal for a 13 year old?

I am 13 and have a size 34B bra and i weigh 123 i have a size 30 waist but my thighs are 34!!! work out 6 days a week and i am a ski racer. I swim and run track. But i still cant figure out if Im under weight or over weight. I was reading that most girls my age are 150 and some are 90. Help?