The shot to the torso has more likelihood to cause death if it hits the right structure. On the left side of your chest are your heart, great blood vessels, and lungs. If the shot was more to the shoulder then an outright kill would be less likely and the risks above would be more prominent (bleeding and infection).
If you didn't want to go with a fracture of the bone from the projectile-- you could have onset of infection (depending on how sick you'd want her to be for those months). Systemic infection can easily cause death. Local infection to the wounds can be problematic as well. You could also go with tendon damage to the arm or leg which would inhibit movement of the extremity. Healing and rehab of tendon and/or ligament damage can take months as well. Whenever an extremity isn't used because it's immobilized you always get muscle atrophy (muscle wasting) which causes weakness of the arm/leg, etc. It takes time to rehab that as well.
Good luck with your novel!