It means that while she knew where she was basically, her emotions were so powerful that she didn't think about where she was stepping and couldn't really form a clear idea of what to do next.

This is hard to say for sure. Typically, "a blind step" would mean that you take a step while not really knowing where it will take you or what obstacles might come from that path. It can be used literally or figuratively. But in this case, the person seems to know exactly where she is and where she's going. So, I don't understand the use here.