How can I better organize t-shirt designs and color variations?

I have a few shirt products and am having a hard time creating listings that make it easy to see what I sell. Basically I have 10 shirt designs and then I have about 50 blank shirts. I want customers to be able to pick their shirt and their design. Right now I have all of the blank shirts listed and then they have to go to a listing and pick their decal. It was the only way I could control inventory, but now I worry people can’t easily see the shirt design options. Any suggestions on how to organize this?

shop is: www.JamiCreatesThings.com