Sounds like you had the zoom set at 75% when you designed the layout. If you do not want to change everything on the layout, you could make a script that changes the zoom to 75%, and another script that sets the zoom to 100%. Open your manage layouts, and on that layout, set the script trigger to On layout Enter perform script set to 75% and then on layout Exit, set to 100%. If that is the only layout you are having problems with. Otherwise you may have to rebuild the whole layout at 100% zoom to have the effect you want.
Another possibility ... Are anchors on? They will enlarge the fields if specified to anchor left and right. See Inspector > Position tab