I think you have done a wonderful job. The 1/4 inch seam allowance is important if you are doing different blocks/sashing so they all fit together. If you have started with another seam allowance, then finish with the same allowance. "Don't change horses in the middle of the stream" It is more important to have a consistent seam allowance than the 1/4 inch. From what I can see on your design wall, it is coming together beautifully!