That's a nice idea to practice shape and it definitely works. Anyhow, assuming that the face is supposed to be symmetrical and the surface flat and horizontal, the facial features as they protrude should be symmetrical in each frame as well (it seems to be dented on the bright side). Unless you didn't intend the face to be even, because looking at it again, the problem seems to stem from the further eye not being accurately mirrored in the full face.