My kids didn't like the English language naming system for numbers 11-19 because it doesn't make sense. DS invented his own names which follow the pattern for other numbers:

11 = Onety-one
12 = Onety-two
13 = Onety-three

etc.

From there he was able to transition to the regular names when I explained that the suffix "-teen" comes from the word "ten", so "sixteen" means "six and ten." That seemed to make sense to him.

To help kids learn the names of the other numbers, nursery rhymes like One, two, buckle my shoe are good. Use her verbal strengths to give her a memory hook for the numbers.