I suspect that what is throwing people off is the hair style?
With the top of your head the hair is quite full looking and high which coupled with a high hairline and flatter more thinned out sides is giving the illusion of a wide forehead.
Your temple regions look ok to me and I feel if the fullness was lessened on the top and the actual hairline lowered by an inch then people would have a different opinion?
I have to say that I think the fullcapwearer you have is very natural looking and once the hairline and density are adjusted then you will have it nailed!