My hair is medium-fine, low density and i had the same issue when i was at APL (now i have it cut into a bob).
I think the problem is due to the fact that washing hair in the shower, keeping the head upright, cause the crown roots to stay flat (parallel to the scalp) and the result is flat canopy and bangs.
To get rid of this problem i wash my hair upside down while if i'm still in the shower (i slightly bend over).