Her hair might just be changing as she grows up. For example, I had super curly 3c hair up until I was about 4 or 5. It slowly turned into loose, big waves before going dead straight for years. My curls came back in middle school and as an adult, I now have 3a/3b curls. All of this to say that you didn't ruin her hair by combing it, it might just be a product of getting older.
(Also is her hair longer now? If her hair is super long, it might be weighing the curls down).