It was in Hannah's faith...
It was in Hannah's faith that God willed to change her circumstances -- God was the one who could correct a situation which was the source of great pain and sorrow to her, even though her husband did not blame or abuse her for her childlessness. And her prayers were answered -- in due time. Even after her vow at the holy place in Shiloh, her prayers were only answered in due time, and there is no way of knowing how much longer after her vow that she waited. Does God answer all prayers? Yes, and sometimes the answer is "No," and sometimes the answer is delayed or held back.