Nai-Nai is a metaphor for the traditional oppression of women in the oriental culture. Her feet, especially, represent the way women were subjected to a delay of growth.
Another good metaphor is to be found in the quote: "By the time my turn arrived, I was left with the tiniest, scrawniest baby bird." (page 73). This shows how emotionally she is treated.
The title of the book is definitely a metaphor: She sees herself as living the life of cinderella.
‘I had seen infants wrapped in newspapers left to die in doorways. Beggar-children in rags routinely rummaged the garbage-cans searching for food’ (p.131/81) In this quote, the metaphor is that of an infant being compared to a piece of garbage, to be thrown away. She sees her own life as having as much value to her parents.
Another good metaphor is that she calls her father's room the 'holy of holies'. In other words the comparison is to a sacred space where only the 'worthy' are allowed.
Lastly, there is the quote: “I only had to stretch out my hand to reach the stars.” (line 61-62) She couldn't literally reach the stars. What she refers to is reaching out for dreams, and trying to make a better life for herself.