I don't have a GO machine, so don't know if this might be a factor or not -
I've noticed that when I cut something out with my ruler, it's usually a teensy bit larger than the ruler - say I'm cutting a 4 inch wide strip, it's actually 4 1/32 inches (or less) - Say I have four "4" inch pieces - 6 (edges - 3 seams) x 1/32 is 6/32 which is 3/8 of an inch.
If this machine cuts an EXACT size, and you are still sewing with the seams you have been using, that might be a factor in why your blocks are ending up small.
Just a thought - - -