Why, when I am drawing faces, might they always come out a bit too wide?

I have noticed that whenever I draw a portrait, the face is wider than the person’s face that I am drawing. It doesn’t look distorted or disproportionate… but I always find that I have to elongate or narrow the face in order to be more accurate. Is this a common error in portrait drawing? It doesn’t seem to be an issue with shading, I just tend to draw the face too wide to begin with.
Could it be as simple as projecting my own image onto my art, just out of familiarity… or something? (I have a broad face, with high cheekbones.) I don’t understand why it seems to be a chronic issue for me, does anyone have a theory?

Artsy jellies: do you have a common error that always pops up in your artwork? Have you figured out why it happens, or do you think that figuring out the cause would lead you to a solution?