You may be speaking from your throat rather than the front of your mouth. It is very hard to get volume and projection from your throat. In fact you'll give yourself a sore throat very quickly if you make a habit of it. The more you need to project, the more the voice needs to come from the front.

Consciously learn to generate the sound from the front of your mouth. You can practice simple vocal exercises in your home or car for this. One is to just say eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee in a low-medium voice and watch where you feel the vibrations and move the effort to the front (hard to describe, but you'll get what I mean when you try it).

I didn't have a problem projecting, but I had a problem keeping my voice in "front" so my voice would constantly be moving back to my throat, which would cause soreness. I had a few sessions with a voice therapist who taught me the basics. I still have poor control and often end up with sore throats if I talk too much at once (especially in medium volume conversation... easier to control in public speaking).

Get some voice lessons if some simple DIY doesn't work. Besides the one above, some of the other basic exercises I was taught include:

saying e ee eee eee eeee with rising pitch.

Repeat with the other basic vowel sounds ooo and aaa. Focus on extended, continuous sound at low-medium volumes, not shouting or whispering. The key is to stabilize your voice in front rather than volume/projection. Once you get the front-stability, it will be easy to ramp up the volume/projection.