How do “Pleading Child”and “Perfectly Contented” have a double meaning in the story? What does the last sentence of the story mean?

Jing-Mei realizes, years later, that "Pleading Child" and "Perfectly Contented" are two halves of the same song.  As an impetuous and head-strong child, the narrator doesn't appreciate all that her mother does for her.  As an adult she realizes all that her mother tried to do for her - buying her a piano, arranging lessons, pushing and motivating her.  She just wanted Jing-Mei to have a better life than she did.   Because she was so young and stubborn, she never was able to value all that her mother sacrificed for her.  However, after her mother's death, she examines the song book and realizes that "Pleading Child," is only half of the song.  The other half is "Perfectly Contented."  This symbolically stands for our narrator.  She used to be a pleading child, who never appreciated what her mother was trying to do for her.  But now as an adult, she is - maybe not perfectly contented - but she is much more content than she was as a child.  Jing-Mei has developed her own talents and abilities, which was really what her mother wanted her to do all along.