Midd,
Thanks for the question.
The key point to understanding what will happen to you is whether or not the RV is dilating. If the RV has significantly dilated since the previous echo, then you need further workup of this VSD. If the RV has not significantly dilated, then continued expectant management is fine.
RV dilation implies that the RV is experiencing volume overload from the left ventricle, and may eventually fail. RV failure can cause a multitude of symptoms, with swelling of the abdomen and legs usually being the first manifestation. This can then progress to pulmonary hypertension and shunting of blood from the right to the left, then with LV failure.
I would recommend that you be seen at a large center to determine the size and function of the RV, as well as the size of the VSD. Assessment of the pulmonary artery pressures is also in order. The testing to do this depends on the center -- you want tests that can answer these questions. Most centers will do this through TTE, TEE, and maybe a pulmonary artery catheterization.
Good luck.