Game Unfinishable as Human defected to Navi

My first play-through I chose to be a human. Towards the end of the game, I am given the choice a second time to defect to Navi. I did this, and at certain point need either a chopper to get to the last battle which I can't get since I've betrayed my human comrades, or a dragon, which I can't get since I am not a Navi or in an Avatar, but still human, leaving me stranded. Am I missing something here. Wishing the save system were a little different so I could choose to remain on the human side....