It sounds like you have lots of images with text wrap on, mixed in with text (without using exactly for line sapcing) and possibly are using returns, spaces and tabs to position the work. This can lead to unpredictability because material can pop over or off pages.
It is also possible you are saving to Word .doc which changes the line spacing and the way text leads off on the first line of a page.
Structure the document more systematically, using inline images, styles and setting line spacing to "exactly".
DO NOT hammer away at returns, tabs and the spacebar to push things into place. Use specified spacing and single tab positioning to layout the document.