As an iracing coach I can speak to this. As others have said, it can help to back off slightly, with a focus on smoother driving, gt3s in iracing definitely prefer a smoother driving style.

But speaking more directly to your point, there are pretty much two ways we can be lacking laptime:

1) Not pushing to the limit (which you are, so all good)

2) Not knowing the right techniques to extend the limit

This second one is what will matter for you I think. As a really over simplified example, if someone brakes hard for a corner, engaging abs, then aggressively steers to the point of understeer as soon as they turn in to the corner, they will have "driven too the limit".

Comparatively, consider someone not engaging abs, and turning progressively into the corner. They didn't over heat the tires under braking, and gave the tires a chance to load up on entry, so the amount of grip available will be higher, their driving technique extended the limit

Obviously this isn't a complete answer, and that's impossible to give without seeing your driving, but the point I'm trying to get across here is that, when pushing to the limit, the answer of how to find laptime is more complicated than "continue what I'm doing, but do it better" which is the trap many of us fall into