I need help finding a book I read in high-school. The details I remember are:

The lead was female high-school aged. The book was based in Australia, she was good/best friends with a boy and I think they would catch up at a particular spot like a barn. I think he ends up going to private school and is good at sports or swimming. His mother’s meek and his dad is aggressive. They end up having sex and then I think the abuse from his father becomes too much and he kills himself. The girl ends up pregnant and her grandmother tried to help her by giving her an awful drink (think I remember it being described as tasting like Marmite) but it doesn’t work. She has the baby and the boy’s parents find out and the boy’s mother tries to help her somehow. I think they all end up in Sydney. I can’t remember how it ends. For some reason the name Sophie keeps popping in to my head but I don’t remember if that was an author or one of the characters or nothing.

Let me know if you think of anything it could be.