Upper register doesn't sound mature enough

Tudor

I'm almost 18 years old and I got to a point where I have no problem crossing between registers, I can hit a G5 anytime I want and I rarely struggle singing any type of song (in terms of technique). However, I often avoid singing in my upper register - and songs that imply that - at gigs because on the high notes above G4 (roughly) my voice lacks a certain crisp that would give it some more character. In recordings, it sounds almost like a very loud falsetto, and I can force myself in any way possible (more breath pressure, more air etc) and it still sounds like that.
Is it normal? My voice has indeed always been a bit behind my age (I can tell by listening to old films and recordings in comparison with friends who were even younger). But shouldn't it start sounding more mature? Should I wait and keep singing the way I feel at the moment most comfortable? Or are there any exercises that could help? Any advice would be appreciated.

highmtn

Stay with your clean voice for the moment. As you progress through the course, you will learn to cut back the air, and at that point you can add some distortion. Don't try to simply force air on your cords in order to make them distort. That will damage them, and it could be permanent.

As you learn to control your air and your tone better, you can begin to manufacture a little bit of safe "texture" that can give your voice a little more character. You will need to go back and clean up the sound to preserve your clear voice, once you learn to distort it safely. At that point you will be able to access both a more textured sound AND a clean sound. You want both, not just one or the other.

Don't sacrifice your clear voice for a rough one. Develop safe modes for all types of vocal sound.

You'll get there. Don't rush into it and hurt your voice by disliking your "plain" vocal sound. Learn more about how to properly use all modes of singing.

Bob