There are three things I can think of that might help.
As you said, you can limit the maximum size of a "can grow" field. To the right of the can grow checkbox (in CR designer) there is a "Maximum number of lines" value that defaults to 0 (no limit). You can set that to however many lines you like.
The details section itself has a setting for "keep together" too -- right-click the details section label and go to the section expert. If you uncheck it there the details section will start on the bottom of the page and continue on the next one.
Look at the page footer section, it is printed at the bottom of each page, and if it is large, it takes away from the available space for the data. Group footers, if you have any, could give you the same problem.