Well, see if you can resolve her situation in such a way that she feels differently about the transaction and wants to change her review to reflect that. Do not respond to the review until you are sure she won't change it, as once you respond the review is locked.
If the review goes unchanged, respond to it politely, unemotionally, and compassionately - saying what you've said here, basically.
"I'm so sorry you're disappointed with the tutu. I use extra material to make them full and fluffy but tulle is see thru and it has to be distributed evenly for a good look.
I hand cut and applied at least 10 flowers for this tutu, but sometimes the flowers fall inside the waves the ribbon creates, so it can seem like they are not all there. Careful arrangement of the ribbon will display all of the flowers. I contacted you to work out a solution to this transaction but [you didn't want to return for a refund, you didn't respond, we couldn't work out a solution, etc.]."