This suggests your footnote separator and/or your footnote paragraph has been formatted with an excessive amount of 'before' space and/or line spacing. Check the paragraph format for both. To access the footnote separator, switch to Draft view with 100% zoom, then click on References|Show Notes to display the footnotes in a separate window. At the top of that window is a dropdown in which you can select the footnote separator.

Alternatively, are you sure the paragraphs that are getting shunted to the next page haven't been formatted as 'keep with next'?

Similarly, if you have Section breaks with a change in the number of text columns on the page, inserting a footnote before the Section break causes everything after the Section break to be shunted to the next page.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]