about my sr9c

i purchased this new pistol with adj sights, go to the range i am shooting 6" high at 15yds, so i adj the rear sight down, i am now on target, but to get on target it is not my natural point of aim, i have concentrate on getting the front of the gun down on target, before i adjusted the sight it aimed nice but poi was too high, is there possibly something i can do to the grip like adding some grip tape on the rear of the grip at the bottom to help get the muzzle up down naturaly

Which way is the back strap turned, flat or arched side out?