I'm sorry about your girlfriends addiction.
As the child of an alcoholic, the deck is stacked against her to be a normal drinker. Maybe she will get help when she does the jail time for the dui. She will have to choose to get help for herself.
As her friend, you may find support through AlAnon meetings or our Friends and Family of Alcoholics section. One of the things I learned at Alanon and here was about the three C's of addiction:
You didn't Cause the addiction
You can't Control the addiction
You won't Cure the addiction
She will drink because she is stressed, she will drink because she is depressed, she will drink to celebrate, she will drink to reward herself, she will drink because you don't understand her, she will drink because you love her, etc.....
She will always find a reason to drink. When she can't she will blame you and start a fight to justify another binge drunk. You didn't cause this, you can't control this.
I hope she gets the help she needs, she is very young.