Polly, I have a sense of what you've gone through. My daughter has suffered from very severe depression as well, and it derailed her academic progress as well. It's what led us to pulling her out of school and onto this homeschooling path. While it's not what I'd have set out to do, it's been really great for my daughter and for me.
I guess I wouldn't assume that because your daughter doesn't have higher aspirations right now, it means she won't ever have them. High school is pretty dull, over all, and she's had to cope with so much in a few years' time. It may be that by getting the GED and then knowing that the MANDATORY part of school is behind her, it'll give her the mental and emotional freedom to start thinking about what she likes, what she wants to do, etc. There are a lot of people who don't discover their interest in something until they're a bit older.
Having my daughter suffer so much with depression made me realize that the most important thing -- the ONLY important thing, really, is having a happy, healthy child. If she's happy and healthy, she'll find her way.
I hope she is doing better -- and you too. I know that once you experience that as a parent, the possibility of recurrences is always lurking in the back of your mind.