I have 3 thoughts.
1. You may need to add in a styler like KCCC to her hair.
2. Give her a hair cut, add a bit of layering to the canopy, it helped my daughter's hair a little.
3. It was around that age that my 3a/3b daughter started loosing her tight curls. She's still curly, but the canopy is almost more of a 2b/2c with a bunch of 3a/3b curls everywhere else. As with many of us, especially when we're young our hair is a very fluid thing. You may find that her hair stays much like this until she hit's puberty where it'll curl up tight again. That's what happened to me, and I think what's happening to my daughter as well.
As an aside, we live In Florida and it's humid as heck here. Humidity shouldn't cause her hair to dry out, but over conditioning certainly can make hair feel straw-like and look stringy as can being protein sensitive. You may want to cut back on the condish or start a low-poo routine in the worst of the humid months. It helps!
For my girls, they get a poo with a clarifying shampoo once or twice a week, and co-wash the rest of the time. To style the little one just gets her leave-in (she just turned 2), and the older one who will be six in Aug. gets her leave-in, some KCCC, and I seal it all in with a tiny bit of Curl Keeper (I tend to use this on all of us almost like you would a serum).
Hope that helps!
Anyone who lives within their means, suffers from a lack of imagination. ~Oscar Wilde
There are only two ways to do things: right or over.