1. Are you currently in the U.S.? NVC handles immigrant visa applications for people who are going through consular processing at a foreign post, while USCIS handles I-485 for people who are already in the U.S. and are eligible for adjustment of status. You mentioned both in your post, but they are distinctive paths.
2. Unmarried child (under 21 of age) of a US citizen belongs to Immediate Relative (IR) category and doesn’t need a visa number. Unmarried son or daughter (21 or older) of a US citizen is a different category which requires a visa number. So when you say your PD has become current, did you mean your existing petition or your upgraded petition? Is your upgrade petition going to be IR (always current) or family preference (depending on visa bulletin)?
Also check out Child Status Protection Act if you turned 21 during the process.
3. If you are going through consular processing (not Adjustment of Status!), NVC will forward the upgrade information to the US embassy or consulate where you will be interviewed. You can call 1-603-334-0700 to check if they’ve verified your request for upgrading your petition.
Since one mis-step could cause delay or more serious problems in your case, you might want to consult an attorney to make sure you are doing the right things.