I am truly sorry to say that there is no hope for your current campaign AFAIK. There are ways to mod the game to extend past the alloted time, normal time, but these changes must be in place before the game begins.

I wish I could help you out some more, and who knows I might be wrong, but I really don't know of anything that could change the outcome of your current game. Unfortunately, that is the danger of starting a game in Late, it might end prematurely.