So, yes, it’s too bad that your daughter has these added stresses of growing-up to deal with. But you can’t change any of that now. The important thing now is to make sure that your daughter doesn’t feel sorry for herself, since self-pity is the fastest road to unhappiness.
I would concentrate on helping her build a self-image of someone smart and independent and capable: then she’ll attract and keep friends. She won’t worry so much about family issues if she has a strong, supportive peer group.
You do this in the usual ways: help her be involved in activities; coach her to be interested in her friends’ problems and lives, rather than just her own; help her develop a love of reading, so she starts to understand the way other people live.
I think sending her to a camp for adopted children might play too much into a “poor you” narrative. Remember that as kids grow older, they don’t just need to feel loved, they need to be lovable. It’s very hard to warm up to someone who feels sorry for herself much of the time—even if she has reason to feel sorry for herself.