I am sure the gravity pushing inward and nuclear fusion pressure pushing outward causes balance and perfection. If pressure is leaving from core outward and gravity is pushing hard on the outside then imperfections should get corrected automatically and a smooth balance should exist.
Look at white dwarfs and high gravity objects, i am prettys sure they are perfectly round.
You're assuming that the two forces are equal and that there are no other forces in play. This is not the case. The Sun's diameter is dependent upon the partial pressures of all its constituent gases (total pressure), the radiation pressure, its gravity and the centrifugal force imparted by its rotation. That explanation is a bit simplistic but serves for this discussion. Of those, gravity "pulls" toward the center while the others "push" away from the center. If the Sun were not rotating, only the total pressure, the radiation pressure and gravity would be factors and each of those would act equally in all directions with its own magnitude. That would result in a perfect sphere. The Sun's diameter is determined by how far from the center those forces are in equilibrium. However, the Sun's rotation imparts a centrifugal force which "pushes" away from the center and this force is greatest at the equator and that causes the expected bulge. Again, this is a little simplistic but serves the illustrate the dynamics.