I got the best results from this:
\usepackage[paperwidth=9cm, paperheight=12cm, top=1cm, left=1cm, right=1cm, bottom=1.5cm, includefoot]{geometry}
And I changed the font to sans-serif:
{\sffamily ... }
Your format was good though, what was your full documentclass?
Looking at the specs of the paper sizes, it looks like you were more likely to have used A6 though.
http://en.wikipedia.org/wiki/Paper_size
I put the document to actual size, and it's only off by a little bit. (The dimensions of the display are 90mm x 120mm but I guess it may not be an accurate ratio. I tried using A5 and I found the text to be too small.