what can i do to lighten my skin grafts? (Photo)

Fractional laser resurfacing (fraxel) with microneedling can improve this over time.  Your goal should be improvement not cure, and a laser physician who is fellowship trained should treat you.  I am so sorry this happened to you.  Best, Dr. Emer.

You have some options to improve your discoloration. I would recommend starting with topical ligthtening creams which can be prescribed by a physician. Lasers can be used to enhance and improve the results of the darkening as well. Often the combination of treatments works best.
If you find the scarring around your mouth is bother some then there might be some options with that a scar revision might help.
I'd recommend an evaluation by  a plastic surgeon as they will be able to address all of your needs comprehensively. I am very sensitive to your concern as I am a plastic surgeon and have had 2nd and third degree burns to my arm and face as a young child.
Your scarring can be improved and then evenness in color can be improved. Unfortunately such a large injury does leave scars but the goal is to help you look the best you can and hopefully this will help your self esteem.
Dr Small