How much do you weigh?

Clearly its a unit of weight if the poll is asking how much you weigh. Stones are also another unit of weight (mabey your familier with this one). 1 stone=14 pounds.

Well, every eating disorder is different, but I'll do my best.
First off, judging by her height/weight, I don't think her life is in danger yet, so that's good, but you're right to try and fix the situation before it's critical.
Second, I recovered because I felt guilty about what my disorder was doing to my family, particularly my mom.
However, this was only a temporary solution. The only way to really fix the problem is to identify the catalyst. One aspect that ties every eating disorder together is that they are all coping mechanisms, some overeat to deal with stress, I under-ate because I had low self-esteem and the only thing I felt I got sincere compliments on was my waistline, and, as is frequent, something relatively innocent soon became an obsession.
My family tried their best, but they made some major mistakes. So here's a survivors advice, all the things I WISH my family had done:
1) Educate yourself on eating disorders and depression. Understand that an ED isn't like a disease that you can cure and it's gone forever. It's like cancer. The recovery is long and she will never be exactly the same. How she deals with that will determine whether her struggles destroy her or make her stronger.
2) Intervene.
a) Have an intervention with a therapist and nutritionist present. Let her know that she has the opportunity to (must) use those resources once per week. Getting the right therapist is critical. In my experience, therapists who have not had an eating disorder actually have more objectivity and have equal knowledge and are therefore more effective. Be supportive but strong, and don't be too long winded because she'll just wind herself up and come up with excuses. Ask her to keep journals of her thoughts, revelations, and food consumption.
b) Give her weight-gain intervals, say 2 lbs/week, a weekly weigh-in time, and a conservative goal weight. She can plan her new diet either by food group or by calorie consumption, and the nutritionist (or internet) can expound upon that. Remember, if you're weight goal is too ambitious, she'll just rebel, and if she truly recovers, she'll gain more weight anyway (when she does, let her know it's a good thing).