I’m 15 years. When my voice is soft, I feel that my singing is very good but when I try and sing loudly it sounds very shaky, it cracks and feels very forced. Even when the notes I’m singing aren’t that high, it still does that when I’m singing loudly. What is the problem or what can I do to sing loudly?
Because you are right in the middle of the time when your voice is changing, there is a limit to how loud you can sing.
Volume in the voice does not come from force. It comes from precise phonation, strong breath support and complete resonance. You need to develop those three aspects of the instrument slowly, carefully and in an age appropriate way.