I finished the Solstice of Heroes and earned the code, but wasn't able to redeem until today. However, now I can't find the code to redeem it. I read that I had until the 12th to purchase my shirt. Any help would be much appreciated. I don't have much time left!
Did you claim the bounty in the game, from the stature, for the shirt?
If so the next step is to go to your profile on Bungie.net and enter the Moment of Triumph section - the code will be there.
If you never claimed the T-shirt bounty in game, though, there is unfortunately no means of doing so any longer since Solstice has ended.