I don't tend to read books with a lot of blatant language and sex, but will read through books where it does have context and is a necessary part of the story. I felt the author was trying to write in a transition for Olivia going from childhood innocence (or as innocent as possible in the environment she lived in), to discovering herself as a teen, but I think she did take the imagery too far. And all of the relationships in the book seemed to be a tainted type of love. There was no joy or happiness and that's what you think of for most first, young loves. I do not think the drugs storyline added anything to the book and could have been left out, without affecting the story at all.
I completely agree with you about the drug storyline. It felt like something else added on top of the bipolar/psychic storyline, even though they were separate. I like your point about the author trying to write in a transition for Olivia. I never really thought about it that way. I just looked at the book as a whole and didn't really focus on that, but you're right! That makes it a little bit easier for me to swallow now.