wow. i just came across your post randomly and wow what a shock for you. i can only imagine how you and she must feel. i took a wayward path as a teen myself (now 36) due to my own poor choices and a dwindling relationship with my mother (mom had "new life" new boyfriend ect.) i did eventually wise up later in life. i don't know if any intervention would have helped me at that point -i had to figure it out myself. i think its important to reconnect (after things calm down) and stay as close to her as possible and do everything you can to enhance her self-esteem. tell her how special she is, how she is priceless not $100 object ect. take as much extra time to do things together just you and her. don't beat yourself up you are not a horrible mother as mine was not either but not living together ect.
Let me be very clear with you.
At the very least, you need to get your daughter into a doctor and have her checked - now.