Can you please send me a copy of this photo via PM if you're paranoid about it being leaked?
I have extensive experience working with EXIF data, there's typically a lot more data than just GPS coordinates stored on it that
might be useful in itself. Most vendors have vendor specific property tags which may yield some useful information.
My current Uni project is actually forensic software centered around EXIF data and creating possible routes a "suspect" took.
I'd be glad to give you my in-depth analysis if you provide the photo. If you have more photos, even better.
Have you maybe tried to crop her face from the photo (if it's higher res) and put it throught some reverse image search? Google have that, and Facebook would be ideal, but I doubt it's possible there. It's a very long shot, but you maybe could get lucky.
You could also try using
http://www.tineye.com/. It's a lot better than the Google reverse image search.
Tineye might be useful but I doubt it'll get any hits. While Tineye does crawl Facebook, it can't get around privacy settings. Also, it only looks for matches or partial matches of the photo itself. It's not going to find you a "similar" face in a different photo, it needs to be (more or less) the same photo.
