Nina Nastasia’s voice wavered and her eyes darted furtively around the room. “This isn’t going very well, is it?” she asked, reaching for a swig of liquor. As adept as Nastasia is at storytelling in her lyrics, she struggled at first to engage the audience between songs, muttering under her breath before admitting that she usually doesn’t talk about her songs before she sings them. She also usually doesn’t perform alone. The New York singer-songwriter,…