spiritedmama.
I can understand your dilemma.

My suggestion is to let it go. Have her study over the summer and eventually when she feels less pressured she will rise up to the occasion. Yes you may feel you are wasting a couple of years but as high school rolls in and with the help of enrichment in math at home. She will bounce back to where she belongs !

We are having to deal with this in Chess. My DS 11 is very gifted in chess but suffers from tournament anxiety and never performs to his potential. So we are letting him chill without the pressure of top performance..He is continuing to learning and practicing in the meantime!
He is equally gifted in math, but surprising doesn't display this behavior ( anxiety for tests/ competitions) in math ( yet !!).

Very cool @ her above 99% scores in WISC and SB5.She definitely has the potential no doubt.
Can you share a few tips with me about those tests ?

Good luck with EOG tests....look for released tests for that grade and have her see some of the sample problems and reassure her she will do great!