they don't fit into little petty places. (4-5)
Part of the speaker's strength comes from realizing when she's in places that don't allow her to be who she is – and realizing, as well, that it's those places which are petty, not her.
they don't like to be held back. (7)
We get the sense that these hips could break through brick walls…or anything else that gets in their way!
these hips are mighty hips. (11)
OK, we're probably not talking Bionic Woman strong, but we appreciate the superhuman quality that our speaker imagines for herself. We could all use a little bit more superhuman strength every now and then!