Julia, are you sure the resolution of your monitor is set right? Depending the type of monitor you can change the resolution to a minor setting (via control panel --> Adjust screen resolution), which results in bigger textsize.

If you want to increase temporarly the size of text you can use the magnifier tool. Ask windows help if you don't know where to look for it.

... no other idea on this

I had a look at your file:
I guess you do adjust your pages to the pagebreaks excel is offering. This suggestions are merely done by the type of paper the printer is set to in order to observe the margins you set.
Now depending the computer I'm using here, the printout will vary:
Windows XP, Excel 2002 won't print your Pg.3 and 4 on one page
Windows 7 (dpi 100%, 96 ppi), Excel 2010 only won't print Pg. 4 on one paper, the others are fine
... but well that was using format A4 in the printer. What type of paper you are using?

Maybe you can try to setup printarea manually. Save a copy of your file before following this steps:
Have a look at
Menue ---> Insert ---> Names ---> define
In the dialog you will find a name (like) "printarea" refering to a range (probably):
=Sheets1!$B$1:$G$220
Mark this formula and replace it by:
=Sheet1!$B$1:$G$50,Sheet1!$B$52:$G$93,Sheet1!$B$95 :$G$138,Sheet1!$B$140:$G$179,Sheet1!$B$181:$G$218
Afterwards you set the margins of right and bottom to 0 (zero).

Have a look at the print preview to check if anything has changed. Still, only a printout will proove if the printer can handle it the way preview it shows.

I know that's quite a job, and probably only the start if you intend to send the whole file to other people. But unless you don't change the outlay I can't think of another way to get it right.



Edit:
Wrong formula, of course you have to replace it by:
=Sheet1!$B$1:$G$50,Sheet1!$B$53:$G$93,Sheet1!$B$96 :$G$138,Sheet1!$B$141:$G$179,Sheet1!$B$182:$G$218