[suzeeq]

For 5" I'd reknit it with a smaller size at the bottom edge and increase up to the correct size at the armholes.. You can take up that much of a seam (2½" each side) then cut off the extra, but you need to be certain that's going to come out the right size. It wouldn't hurt to wash it first to see if it shrinks, grows or stretches more one way than another. Then see what size it comes out.