Gifted girls are adept at hiding their abilities. They adapt to their surroundings in order to try to fit in. So if your DD is testing perfectly average, it sounds like she has done a perfect job of blending in. And since perfectionism is another trait of gifted children, I wouldn't be surprised to learn your DD had figured out what score she needed to be perfectly average, and missed just enough answers on purpose.
We caught my own DD7 doing this. She went to pre-K already reading picture books, and printing with penmanship I could only dream of. That pre-K teacher celebrated her abilities, and she got the chance to shine... reading aloud to the class, for example. Then came K. A few weeks in, she came home with a mess of a paper, and tried telling us she had forgotten how to write the letter M. Needless to say, we weren't buying it.
Emotional issues, check. Not wanting to go to school, check. Acting out at home, check. In our case, we recognized the problem immediately, and after advocacy failed to yield tolerable results, we yanked her out and homeschooled her.
As an FYI, the term "highly gifted" is usually reserved for those with an IQ 145+. The range 130-144 is considered "moderately gifted." This is also the range my DD tested into.
