Your video likely has some stray clips or frames floating out on the timeline, making your movie appear to be longer than it is.
To see your entire project timeline, press the \ key (above the Enter/Return) on your keyboard. Most likely you'll see a 34 minute timeline with your 14 minute project at the beginning.
Now click and drag over the the empty space beyond your movie to select any stray clips or frames and then press Delete on your keyboard. When you've got all of the strays, press the \ key again and your project should appear at the right duration.