Apart from the lack of breasts every other 'feminine' pose has been adopted. Hair, body language, 'sexy' poses....
I think a lot of girls, at around about the age of 10, are in certain ways at their peak, and the dawning awareness that soon you will grow breasts and start to menstruate can come as a shock. It feels like the end of of innocence and freedom, and a sudden hiatus in ongoing journey of personal development.
The body can feel like one's fate - and you know that on account of it you will have to deal with certain types of expectation and experience. I can very much understand girls wanting to be frozen in pre pubertal stage - and that seems to me to be what motivates her.