I put the front dot over the bullseye with my fnx9 and fns40 aka combat hold. Both guns have the factory trijicon night sights, and the front dots are smaller than the standard front dot, which is huge. I was dead on at 7 yds, and all my rounds were in the kill zone on my shootnsee targets. I agree that your issue is how u are gripping and holding the pistol. Practice practice practice n good luck! btw, start at 7 yds, then move farther as you get the hang of it
I'm not going to arm chair your shooting. On my first visit to the range with my FNX 45, 25 yard shots holding at the top of the head were hitting center mass. Now at 400 rounds through it and dayly dry fire practice the same hold is resulting in hits in the lower throat. 5 shot groups are very consistent about the size of a fist. Shooting rate about a second between rounds.
I would shoot it off a rest. I've done this with several pistols I was either shooting left with or low and come to find out it was mostly me having the issue (I did have one pistol where I needed to push the rear sight a little to the right). I have had my friends do this with their pistols as well, especially when it's a new gun.