Yep, I agree. I am guilty of reading my son's journals. And a good thing I did too.
I never let him know, but because I snooped and knew what he was thinking and doing and feeling I was able to steer him in different directions and if I hadn't done what I did, he'd be in jail instead of an ex...
When I was about that age I drank cough syrup too. Actually Vicks 44. I loved the taste. Did not know it was addicting.
However 6 bottles? I would take a good look at who her friends are. Who she hangs around with at school. And I would probably do it very subtly so as to get the answers...