You could add to the foot of the sail if you either stand your mast up a bit straighter or lower the back of your seat or both. Us biggins always seem to have that problem of boom hitting skull.
I manage to have my boom down near my ear and swap sides by ducking under as I turn releasing a bit of tension on the sheet as i do it. When I can plan ahead for a turn i can duck under before a turn making the transition smoother