It's as if my prayers have been answered. An angel from the National Visa Center sent me an email today.
They responded to my request to research our case - to see why the US State Dept/Embassy could not find where they'd ever received our case file - although Chicago USCIS and the NVC showed it'd been processed and forwarded on.
The NVC's email provided a Corrected case number. They didn't specify whether the original case number we were given in writing was incorrect or if they had replaced it with the new case number...but suggested I contact the US State Dept/Embassy and follow up, using this new number.
When I called the US State Dept. today, a nice lady pulled up the new case number and said "Oh yes, I see here that it has been received and fully processed. The P3 Packet has been sent to Korea (to the E.S. Welfare - the Korean adoption agency). They should be scheduling your child's Visa interview very soon". I found myself in tears of joy and overwhelmed with grattitude to the Lord for hearing my prayers!
So, at this point...we could be looking at just a few weeks before we go to Korea! I will just need to check back with the US State Dept. to see if the Visa Interview has been scheduled...once that happens, things should move along!