It sometimes matters, as some issues with a certain test may indicate potential further issues to explore. She does not need to have significant impairment in multiple settings as that was a DSM-IV requirement. The DSM-V and TR version simply states there is "clear evidence" of impairment or interference, and the impairment does not need to be significant.
To be clear, are you referring to issues as in impairment or issues as in symptoms?
Developmentally gifted kids may be ahead so they should be assessed against developmental age, not chronological age.
However there are many other issues that could cause forgetfulness so be sure to go to physical doctors too and other professionals as necessary.
