I hate to do this, but here's what it seems like you're pointing to as evidence of tracing: http://img.photobucket.com/albums/v228/Celarania/Sample.jpg (NSFW) Notice how the butt, back, and even the space between the legs line up. And this was done without real time scaling and rotation in gimp, I probably could have gotten closer still in photoshop.

Now I don't think that you did trace that or have ever even seen that photo, but I could get a few areas to line up well, with the same ratio. If I could do that with a photo you've never seen, this artist could easily have what you're doing with references either to the art in question or to the same reference, or whatever.