Are you using A4 or letter size paper? they are close, but not the same.
A4 is 210 X 294 mm (about 8.2677165" X 11.574803" [my Sharp Calcuiator]) Letter is 8.5" X 11" ( 215.9mm X 279.4mm)
So the letter is a little wider and a little shorter than A4. Since letter is what is easiest to find here in the USA. You might still be doubling up on the last line once in a while. At least the print previews might be a bit off