Letter from my psychiatrist:

This is a 16 year old girl with mild to moderate depressive disorder and traits of emerging borderline personality disorder, being treated with fluoxetine 20mg. She has a 2 year history of chronic feelings of low self esteem, poor self image, dissatisfaction with her appearance and eating disorder. She has lost weight by limiting intake, increasing exercise and on some occasions, has got into a binge-purge pattern. She has also managed her mood by self harming behaviour though less so recently. She is an intelligent girl who sets herself high standards and is critical or herself, compares herself unfavourably to others and tends to predict that others will judge her unfavourably. I think this has contributed to her low mood, some degree of social anxiety and led into her eating disorder and self harming behaviour.

How serious is this diagnosis?

Look at the mild to moderate part. It doesn't say severe or serious.

It means there are issues several in fact... they should be controlled with medication... and some issues may be the cause of other issues she is suffering from.

If they had said they recommended institutionalizing them, that would have been serious. I take from this they believe it can be treated.

Her main problem is control, which diagnosis can be managed with proper use of drug therapy (correct meds and patient's compliance) and counseling to figure out what she can control and how. The doctor's mention of her intelligence and high standards bode well for her future, that she can become happy and mentally healthy.