Got her booster!
So, I got DSD her new seat. We went with the HBTB in "Girls Rock" and she loves it!
It fits her well and she's still got some growing room (at least 2-3 notches on the headrest settings)
I got a really great deal on it too. Found it in a local Target on sale for $45
Thanks for all the suggestions and help ladies
She is very proud of her new seat and tells almost everyone about it and how much more comfortable, safer, and what a great view she has. I love the fact that DSD is now riding safer, at least when she's here. (her mom wasn't too pleased