If you want to stay at 12" finished, you could try one of these:
[ATTACH=CONFIG]429438[/ATTACH] [ATTACH=CONFIG]429439[/ATTACH] [ATTACH=CONFIG]429440[/ATTACH]
The center square is 7 1/2" finished (so you can use your 8" pieces). In the first one the corner squares are 2 1/4" and the 3 center pieces are 2 1/4" X 2 1/2" finished. In the second & third ones, the corner squares are 2 1/4" and the elongated flying geese are 7 1/2" X 2 1/4" finished.
Hope these help! Good luck and show us pics!!