Blood Price by Nicole Evans:
 
The law of the gods is those who kill must pay for it in blood.

In the land of Armadin, where nine clans exist in a fragile peace, Ashilde is one of the few chosen to pay the blood price. Through it, she becomes a warrior, capable of killing to protect her clan—alongside her hunters, who provide the essential animal sacrifice, lest they become the next clan to suffer the gods’ wrath.

When an attack wipes out their few remaining hunters, Ashilde must find a way to protect her clan and still appease the gods, despite her shaken faith. But when her monthly bleeding stops, she can no longer kill. Cast out by the gods’ decree, she’s given a single task: travel to the gods' realm, atoning for the failures of the clan and herself alike. If she dies, another will be sent in her place, until the demanded atonement is fulfilled or her clan is wiped out. Entirely.

Bound by a promise to protect her people above all else, Ashilde embarks on a quest driven for answers. Aided only by a pair of animals and a small child she meets along the way, Ashilde must battle the elements, her pursuers and her own mind to reach the gods’ realm.

To save her people, Ashilde’s journey forces her to answer the ultimate is she willing to pay the price asked of her, now that she can no longer pay in blood?