I'm so sorry to hear of the ordeals you have been through.
This graft versus host disease appears in its acute form within 100 days after the transplant. Then, a chronic form can appear about 3 months or more after the transplant.
This can, indeed, affect your skin. Usually it is treated with cyclosporine and steroids such as prednisone.
Here is a link:
It is not the place of any medical professional to tell you how long you have to live. As you say, already, you've beat the odds, and everything like this occurs for a reason.
Do you mind my asking, how do you feel about all of it? What do you want to do in the time that you have left? What is important to you? What things have you discovered about life from having this difficult illness?
There is a natural remedy you may want to try for the liver toxicity. It's an herb called milk thistle. It is not a drug and you can get it at the health food store or online. Maybe it will help, or perhaps not...but it can't hurt. It is simply a natural way of removing some toxins from the liver.
What kind of support system do you have?
Do you go to transplant survivor support groups of any kind?
Good luck to you and I do hope this helps in some way.