Another thing is, what kind of rotary cutter do you have? Have you tried one of the ergonomic ones. I really like my Martelli They make a righty & a leftie
here's what they look like:
http://www.amazon.com/Martelli-Ergo-...+rotary+cutter
It would be great if you had one you could try first as I use mine standing. I actually alternate a 'regular' fiskars straight handle type with the martelli. use one for a while, then switch.