about your paper piecing being off--sometimes when you run something off on a printer (either to print or to copy) it will do some resizing automatically to fit the paper and existing margins,etc. Often with templates there will be a marking that gives the exact measurement so you can check what actually printed. Maybe this is what happened?
if that's not it and there's a whole 1/2" difference, then it's likely that the seam widths are off and you probably need to deal with that. sorry you are having this difficulty--think most of us have been there.