Could it just be that she needs comfort at night. I know my DS would just nurse for comfort at night. She might not be hungry, she probably just doesn't know how to put herself back to sleep after waking up. Good luck mama, I know it's hard. My DS was a terrible sleeper at first. Once he started eating table foods he did sleep longer but it could just be coincidence.
Michelle, mama to Genesis, Abram and Juliette