Ok, from someone who smoked pot for MANY years, and who has fought issues with depression his whole life…
There’s only 2 things you need to do… bottom line…
-
In-patient Rehab (even though I don’t think the drugs are the main issue, as pot wasn’t for me, nor was it addictive for me; I used to quit for months/years at a time)
-
Psychologist/Psychiatrist mental health time. Get her to see one; ASAP; in-patient if you need to.
Basically she’s got a depression/mental problem (most likely from moving and leaving everything she knew) and turned to pot; that in turn at 17 is just making it worse. Gotta get her off the pot and onto some anti-depressants. If you can achieve those 2 things; I think you’ll get your sister “back”.