Even if you feel your grip and resulting accuracy are acceptable, I bet you can take accuracy to the next level with a two thumbs forward grip. Don't give up if it doesn't work better right away, practice dry firing to see which exact grip holds those sites 100% steady after pulling the trigger. Once you get the grip that is steadiest, then practice that muscle memory when picking up the gun. Repeat as necessary to improve muscle memory. You should be able to do this without ammo, in your bedroom, within a half hour each time until it feels like the only way you want to hold the weapon.
We haven't talked about trigger pull, but I assume everyone knows to only use the tip of your index finger on the trigger (this is common to all firearms, not just pistols). I have big hands, so I must bend my right wrist back almost as far as it will go in order to keep my index finger from protruding through the trigger guard too far. This has a hidden benefit of lining the backstrap and recoil from the pistol up with the center of my forearm. Again, even a single handed grip is far from natural for me because of this.
I will admit that I am envious when someone says they can be acurate without much effort on the grip, since it has literally taken me years to refine my technique to the point where I can hit dead center to where I aim.
I assume by tip of the finger, you mean about midway on the pad between the distal joint and end of the finger? If you mean the actual tip, I don't agree.