Actually, I think you said the right thing. If she screwed up on the test, unless it's something I've just never heard of before (something special to her field), she can actually take it again. Also, considering it's a big deal test, she probably feels as though she did worse than she thinks.

I struggle with similar things, though my son's only 9. I have been working on trying to get him to "stick with" things that are hard because like her, everything is usually easy for him. I've read your posts for almost a year now and you seem like an awesome parent. She's just scared. And you did the right thing.

I hope she did great! But if she didn't, remember to remind her that she's not finished because of one test!