If you hit under the spine she would be dead and there would have been a lot of blood on your arrow. You hit above the spine and went through the backstraps. It may have hit the fin type protrusion from the vertibrae that stick up a little, which would have slowed your arrow enough to not get a pass through. If your arrow is out of her she should heal fine. If there is some still in her she will be lucky to not die a terrible slow death from infection.