With a 10-20mm, for me, its about what it does for perspective rather than just "getting a lot in"
Setting your lens at f8 and manual focus at 1m will give you a depth of field from ~ 50 cm to infinity.
Try changing your position - lie down or standing over your subject and see the different images it creates
<<<lying down>>>
<<<or standing tall>>>
both taken within ~ 5 feet of the girl
<<<more lying down>>>
<<<and more>>>
<<or standing over the subject>>>