3D Touch works bad

Hi all, a few months ago my iPhone screen broke and as there are no official Apple stores in my country had to repair it with no official services. Since the screen broke I went through several technicians and changed more than 5 times of screen and I still have the same problem. none of the screens is responsive as the original, sometimes when typing very fast the screen does not take the letters correctly. But the biggest problem is that the 3D Touch does not work as it should, there is no difference between the 3 levels of pressure and it only works when I use my thumb. It's as if it only works when I use the entire surface of my thumb. no matter how hard I press just to support my thumb with the largest surface of my finger the 3D Touch is activated. Has anyone else had this issue ? ifixit screens work in the same way as the originals?