Is it normal for hair volume to be less dense on top of your head than the lower back of head / neck area if you still have a full hair line up front above your face?
On a non-balding person the hair density is similar throughout the scalp, but there are areas where the density may be lower, like the sides of the head (above the ears).
Only the area in the back of the head (a 2 1/2 inch area) is considered permanent, as shown in the hair that remains in the Norwood class 7 pattern.