Your picture indicates that the length of your binding is too long. It has nothing to do with the width of the binding-2 1/2 inches vs. 2 1/4 inches. I have used both my regular 1/4 inch foot and my walking foot to attach the binding with equal results. If I have pinned the binding with a bit of excess of length, it works out at the corners.( I always pin my binding on to start with so I can be sure I don't get to a corner with a diagonal seam in the binding.) I have found that I have to be careful about joining the two ends of binding at the finish so I don't have excess fabric. I cut it a bit short to be sure it fits. Yes, I have had to take stitches out an re-cut the ends a few times. But, I always am happy with the result.