In the end, we decided to make it a duvet cover because we figured we would get more use out of it. I simply sewed an old sheet from the thrift store to the underside of the quilt and added some buttons along the bottom. I also sewed a bit of ribbon to the inside edges of the duvet cover and the outside edges of the down comforter to prevent it from slipping.
Honestly, I can't believe this quilt thing worked out. Three weeks ago, I learned how to quilt a pillow, but I still can't get over the fact that I was able to translate that meager knowledge into a finished project as big as a whole quilt.
There were many scary points along the way. For example, we nearly ran out of denim fabric, the fabric wasn't long enough, I couldn't get the squares to line up. Yada. Yada. In the end, it really came together. I'm still not exactly sure how, and, at this point, I'm not up for trying it again.
However, it's been such a fun process: receiving fabric in the mail from friends and family, building squares with Matt, piecing it together. We feel really proud of the finished product and it will have meaning to us for years to come. Hooray!