You have done what you can to locate her. I commend you for searching two days and asking for ideas. The fact that you did not find her after searching for two days means she may have survived this long. If you hit the front of the shoulder and she was running fine, she may survive. Several years ago, a guy from work shot a buck. They later discovered this buck had three additonal slugs in the body from a previous season(s). You need to chalk this up to experience, and put it behind you. If you are hunting in the woods, you may not always see all the branches in the flight path. Always do your best to check the flight path. If you can, use something with magnification (binoculars) to check for obstructions between you and the target.