As far as Michael Moore, I think he has some ethical problems. He lets his zeal get in the way of his message. He also lets his hatred of George W. Bush get in the way of his message. I agree that he misused your photo, and should have asked permission to use it at all. Your lawsuit may not succeed, but it will make a difference.
Michael Moore's imperfect message does not make lying the country into war an honorable act. It does not make kidnapping, torture, bombing, killing, and war profiteering honorable things to do. It does not make the deaths, maiming, and psychological damage done to American troops justifiable. I can say that George W. Bush is a sociopath without hating him, because he is a sociopath, and hate is a harmful waste of energy. It's enough to say good riddance.
You do a brave thing taking pictures in a war zone. You may own the rights to the photos you have taken, but that does not mean you own the truth of what the images show. It is an easy thing to confuse. This war has been a great tragedy for everyone involved, except maybe the executives of Halliburton, KBR, Blackwater, and kindred spirits. The greatest tragedy is the death and destruction of the people and property in Iraq, but for Americans, the harm done to our armed forces is immeasurable. As your picture shows, good, compassionate people were sent into an impossible situation, and their lives were forever changed. I suspect that for most of them, it was not a change for the better. We will be paying for this debacle for decades to come.