Paper piecing is a good idea for this pattern. Also I would double check your seams:
http://www.quiltingboard.com/tutoria...ce-t89997.html
Remember that your seam allowance can change with fabric and thread combinations. I just started a quilt and one of the fabrics is a bit heavier than other quilting cottons. I didn't check my seam before I started & after assembling the first block found that it was in the wrong spot for my thread/fabric combo. I moved the needle over one more click & it was perfect.