do you think i am over reacting and over concerned

I have a cousin who is 16 her parents split up 2 years ago and her whole life has been turned upside down she has lost her family home and her and her mom have been forced to live with my grandmother, her dad is loaded so when ever she goes their it is like a shopping spree in all shopping centres .When I lived with my grandmother when I was younger because my parents were saving to buy a house she always made fun of me,but now she is there I just want to hug her and tell her everything will be ok. Recently she has become vegan and has lost 3 1/2 stone and is super skinny and she just looks like a pile of bones, she is also constantly getting drunk and now is sneaking out with older lads who are in their 20s. Is it bad I want to shake her and tell her not to do it and want to take her to an AA talk where people talk about how they became an alcoholic ( 2 of her friends are). Is it bad I feel so concerned and worried about her. I want to tell her everything is alright and that i will be there no matter what and If she needs me day or night she just has to ring and I'll be there.