If your current software is working for you and all you are having trouble with is the printing size....I may have a solution for you...and its free.
Go to this link and download the FREE Cute PDF print driver and convert your drawings to PDF files and then print them out any size you want. That would be easier and faster than learning a new, more expensive program.
http://www.cutepdf.com/download/CuteWriter.exe
Going to a different drawing system is going to cost you. I use softplan which is nearly $3K....even the LITE version is almost a grand. But...I can crank out a floor plan in less than an hour....faster if I am drawing what someone has sketched out.
Anyway...hopefully the above solution with help.
Sam