I am a big believer in pressing. Why don't you chain stitch the first strip on one side of the 5" square. - do this to all of the 5" squares, then press. Go back and do the next side to all of the squares, go all the way around the squares by chain stitching, press then on to the 2.5" strip, repeat. Pressing is very important to making a squared block. Hope this helps.