If I am reading this right..you are starting with a 3.5 x 2 rectangle..then sewing on the diagonal line across the 2" sq. on both corners of the rectangle. This will give you a finished flying geese unit of 3.5 x 2. Is it suppose to be 6.5" square when finished? for it to finish at that size you would to start with 2.5 x 3.5 rectangle, sew 2.5 sqs on each side then put 6 of those units together. Two sewn across by 3 sewn down. I hope I haven't totally confused you..
Happy Stitchin' Linda B.