It is about an 18 year old girl who found out she has cancer (bone or lung). Her and her boyfriend Sam have a baby and she moves out of the house to raise her child with Sam. Sam plays the guitar and the girl's leg bothers her in a few chapters. In one chapter, a doctor comes to the house to talk about something (I forgot what it was) and the girl said no. Sam was angry with her for saying no and the girl replies that "Sam, it's not your decision!". Sam then storms out grabbing his guitar.
That's all I remember

Please help... I think the title starts with a S but I'm not positive
:) thanks

Sunshine
Sunshine by Norma Klein (http://www.fantasticfiction.co.uk/k/norma-klein/sunshine.htm)