Photoshop :: Reducing And Enlarging An Image

I've got a sewing pattern that was drawn by hand. It's larger than a standard sheet of printer paper (maybe 14"x20" or so). I scanned it in two pieces and matched those up, then used the pen tool to trace around the original pattern and stroked the path. Now I need to reduce the whole thing in such a way that if someone else were to download the file and enlarge it by the same amount (or trace around it with X amount of added space all around) it would match my original pattern. (Gee, does that make sense? I hope I explained it right.) I have tried changing the image size, saving it as a new file, and then opening that new file and enlarging the image size by the same amount I reduced it, but when I print it (just allowing the lines to go off the edges of the paper since it's too big), it doesn't match my original.