There is nothing wrong with size slim clothes. She probably just has a high metabolism, and it will probably catch up with her when she hits 30. LOL! Like me!

As for skinny long jeans, if you have a western wear store around, they may be able to help. Most western clothes are extra long to accomodate boots (it's the western style for jeans to bunch up around the boots). Therefore, the long jeans. I'm 5'7 and wear a 36" inseam. Wrangler 20X are nice and stylish, at least I think, and aren't too expensive (around $25). Rockies, Roper, and Cruel jeans have more styles and colors, and are a little more expensive (for adults, up to $60+), but some stores have racks of jeans that are slightly irregular for much less ($14.99 last time I got some).

Just a thought.

I have a tall skinny child, too. DD7 comes up to my chin. 8slim (in "normal" jeans, not western) are too little, but the regulars fall off of her. She loves her western clothes, though, and her red boots!