Hey Mel, thanks for contacting me. I checked into it and have added the t-shirt coupon to your account. It will automatically show up in your cart when you go to check out, but you have to click it to apply. When you do, you’ll see the cost of the t-shirt go to zero (shipping too!).
We had a few people who purchased multiple registrations, and this was problematic for our system. It requires some manual intervention to sort out the coupons. We’re working to improve that for next year. 😉