Do you mean that you project the photo on the paper and trace? That is how I do it. If you are drawing freehand with no projection, are you using the grid system? Are you using ellipse guides? We do that with large mural paintings. To get perfect perspective I need tools, working from the horizon line in 1, 2 or 3 point perspective. A long straight edge or string helps work out large murals.
The drawing below was done with ink, markers, gauche and chalk. It was freehand with the use of sweeps and ellipse guides. The 'eye-balled' perspective in my drawing is off a bit because of time restraints. But, had I the time, I would have taken a photo of the Camaro and projected it as a base for the final rendering.
The eye is good, but not perfect. The car we built, from the drawing, is below. The car was finessed as it was built. As you can see there are more compound curves and deeper sweeps in the final outcome. A very nice form.
Your drawing is picture perfect with regards to perspective.