It’s natural for a child your daughter's age to be asking tough questions. Her critical thinking and ability to empathize with others is developing. You mentioned that she is no longer satisfied with your generic answers, so it may be in everyone’s best interests to give her a little more. Children often ask questions because they have heard other kids talk about it or because they saw something on TV. They are merely curious. That does not mean that since they asked, you have to tell them everything.
In your situation, it is perfectly OK to say that you simply do not know everything because that is the truth. Telling her of the drugs in the house, the unsafe friends, and the inability to provide food and shelter, might satisfy her curiosity. Make sure she understands that decisions to have children live in a place other than their original home are not made lightly. If you’re wavering on disclosing a specific detail to your daughter, then that might be a sign that your daughter can’t handle some of the information yet.