well my 12 year old dd is probably about 5 ft and 75lbs. she has always been thin. i don't worry about it, she's healthy and happy and looks great to me
i bet your dd is fine 

Be a part of the community.
It's free, join today!

She is short for her class, but also one of the very youngest with a later summer birthday. She is very thin but doesn't look sickly or anything. And that kid can pack away the food! Just has the metabolism of a hummingbird. Yeah, I did too at that age; I remember wearing slims. Nothing that puberty won't fix!