You are correct. There are a few states that tax telecommuters in their state, but Virginia is not one of them. You would only be taxed on income you earned working within Virginia, and in your case, you wouldn't pay taxes to Virginia then either. DC and Virginia have a reciprocal agreement that states that if you commute to Virginia from DC, you only pay taxes in DC.
To get back the taxes withheld by Virginia, you will need to file a Virginia nonresident return, and then select the option marked in the screenshots below (your situation is similar to the Military Spouse situation. As a telecommuter, you didn't physically commute to VA from DC, but VA can't tax your income anyways. If you select the DC option, however, this is also acceptable).
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