I have trouble projecting when I sing. When I project, the notes end up sounding off key and shaky. What do I do? How do I make my voice stronger?
I think projection is a misnomer. We do not project the voice. We become so full of a sound that is acoustically efficient that it spills out of us in every possible direction – from our front, back, sides, head and feet. Sound waves are not uni-directional. They are spherical.
Force is a very inefficient way to increase the volume of the voice and would produce the shakiness and pitch distortion you describe.
Refined phonation, perfectly paced breath flow and RESONANCE create volume without force.
The best is if you can work with a teacher to learn some practices. You can read items here about breathing, phonation and resonance for ideas to get you started.