I've now transferred this quilt from the sheet to my design wall. In the process I tried several other arrangements of the elements, but kept coming back to this one. Now I just have to figure out where to go next.
This afternoon I've been looking through a couple of my quilting books for some inspiration.
The cover of the second book has convinced me that my design isn't really looking too round after all. I could simply rotate it 22.5 degrees and border it up to the desired size. Even if I choose to add more to the star I may just give it that little rotation. I'll have to keep thinking.