Unfortunately, unless something like that was a condition of your plea agreement, there's no provision in your state law to reduce your felony to a misdemeanor after the successful completion of your sentence.
Unfortunately also, the state of Virginia does not expunge criminal convictions unless you first receive an absolute pardon from the governor based on your actual innocence. These are extremely rare.
You could have more favorable results with what they call a simple pardon. While that would not allow for the expungement of your records, it would still be official recognition from the governor that you turned your life around and should be helpful to you on the employment or housing fronts. You can find out more about the simple pardon here.
Pardon's are free to apply for, and you don't need a lawyer to do this for you.
There's one more option, but that would require the services of a lawyer. It would also be very much a longshot. And that would be to retain a lawyer to reopen your old case and petition for the judge to reduce or dismiss your felony in the interest of justice. Even though, as I said above, there's no law providing for such a reduction post-conviction and sentence, a judge has the power under principles of equity to do something like that to prevent an injustice.
They are very cautious and sparing in their use of this power, and some will refuse to entertain a petition on these grounds at all. But others will do it to prevent an injustice.
You would need to talk to a Virginia lawyer about bringing the motion. He will have to draft it essentially showing why the law under which you were convicted should be ignored in your case. There would probably be opposition from the prosecutor. So you might want to get some free or low cost consultations to get a sense of how likely this is to work in your jurisdiction before you pay a couple of thousand dollars to a lawyer to try to get this done.