Did you put your ingame name, Your real name, and your address in the note with the donation, and request a t-shirt in the donation?
If you missed some of this information, you could pm Artimus with the rest of the information, but he has to have at least your ingame name or your real one with the donation to confirm that it was you.
I would suggest that you pm Artimus anyways, and see if you can sort it out.