The Lovely Bones: too much censorship?

It was rated PG-13, so why did they insist on leaving out a lot of the details that made the book. They never acknowledge that she was d before she was murdered, where's the affair with her mom and the private investigator? and what about when she transfers to Ruth's body and the shower scene with Ray? The dumbed down the book and added to much CGI. Also, HOLLY WASN'T KILLED BY SUSIE'S MURDERER. So why did they connect that in the movie? I thought it could have been more powerful. The book brought me to tears multiple times and the movie did nothing for me.