What is the author's tone in the memoir, Happiness?

The initial language of Heather's thoughts as she leaves for California alone, about to become a single mother, reflects the hopelessness and desperation to be comforted. Despite this, Heather's description moves to a more hopeful, future-looking mood when her daughter is born ill, representing her presence in her own life. However, as the novel continues, and Heather reconciles with Brian, she begins understanding more about how she has changed and her own voice becomes much stronger. Her language becomes more aggressive and searching to reconcile who she is as a mother and a partner.