J.P.
Are you and her father tall people? Perhaps its a family trait? If not, I was one of those tall girls that was head and shoulders taller than my peers until puberty, then I stopped growing. My parents were worried until then, but there was nothing else wrong with me. My weight was good, I was in great health, no other signs of puberty had started...I was just a tall girl (and the center of rec. basketball, LOL!). Now, I am a 37 year old woman that has been 5'9" since 6th grade...ha-ha! If her doctor doesn't see anything out of the norm (perhaps there's some blood tests to check her hormones and thyroid), I would think she's just one of those tall beautiful girls that every class seems to have (and most supermodels were as well).