Needlework Parallelogram

My next Show and Tell will be the blocking of this piece of needlework, followed by the construction of a throw pillow.

The top edge of the worked cream border is lying along a straight line. Remembering a math class, I dubbed it "the needlework parallelogram". It's off 3" top to bottom on the left edge and 3'1/2" along the right edge! This is going to be a challenge.