when is enough, enough?

I went to Brooklyn about September to pick up a girl we have custody. That was after working all day, from 7 am; we got home about midnight-1am. She AWOL'd from a local group home. She is 16 and in no way ready to be on her own. She had hopes of going to an independent living program but was not doing what she needed to do. She had agreed to go back and get her shit together and do what she needed. Well, she didn't, so I had to look for another placement for her which meant a higher level of care to a facility in Buffalo which is 4-5 hours away-one way. She AWOL'd again in November, and has been gone since. In the mean time, she turned 17 in December. I think the mother knows and has known where she is the whole time. I was figuring she would resurface about the time of her birthday or Christmas; she didn't. Then I figured we'd hear from her this week because her 14 year old sister is due to have a baby this week. Great parenting in that house. I had just conferenced with my supervisor early this afternoon about what to do with the matter since we have court next week to review the arrest warrant that was issued on her back in November. The boss said cut her loose; the county attorney and the judge will say she's going to be 18 at the end of the year and what will they do with her-if they find her? Haven't we spent enough money on this kid, who just doesn't get it or want our help. We have had custody of her for 2 years and she hasn't changed in 2 years, why would she in 10 months? I have this bad feeling that if she turns herself in, she will be telling me that she is pregnant.
Guess what.....there was a message from her on my voicemail today saying she was going to turn herself in next week when we go to court. I was shocked. I was about to close the case, and now I will have to deal with her.
I hate to think that we waste our money on kids or that we give up on them, but I al also a realist...and I hardly ever see progress. I found out yesterday that another girl on my caseload, who isn't doing what she needs, is pregnant; she is 17. I used to cry when I found out these kids were pregnant; I felt like they were my own kids and I wanted to shake them and tell them you could have made something of yourself; we took you out of a bad situation and gave you an opportunity. I felt like I couldn't save them.
Makes me wonder why I get up and go to work everyday.