I think that you need to address a few issues with her. I think that you should let her know why you had her take the test, i.e. Mom wanted to see if you needed a different program in school, and why you don't think that it is good for her to have the number, i.e. I've seen too many people place artificial importance on the number and get into a fixed mindset. I also think you should listen to her about why she thinks it's important to know. Once you know that, it might make it easier for you to address it in a way that you feel comfortable.
I've only had one of my three kids tested and she is HG and dyslexic. The 2e aspect made it easier to talk about how different tests measured different things. We ended up having a conversation about her results to allay her fears. She worried that the test showed that there was something seriously wrong with her and mom was trying to hide it from her.
This may be totally off base. Maybe your daughter is worried that she has disappointed you and that you are ashamed of her results. Her laments about being "average" may be her way of seeking reassurance from you.
