I think to have a truly powerful image, it should be only and image. A picture speaks a thousand words and all that.
People should be able to tell what is happening in the image, without it being too blatantly obvious.
If i were to go about it, the first idea that enters my head would be an upset, crying girl, lots of running mascara, preferably with black hair. I would have her slouched over a desk, head resting on her arm looking just past the camera. That would be the bg, slightly oof, and in the foreground, an open pair of steel/chrome scissors, possibly with the tiniest amount of blood on the blade.
I don't think you need to see scars, cuts, scratches or blood. With something like this, i think what you don't see will be more powerful. Kinda works well with the idea that a self harmer will always try and hide it too.
Sorry, i know it's a completely different idea and not really critique on your shot. I get a bit carried away some times.