Adjustment of Status - I-485

Hi all. We've been lurking for a week or two but now have a question of our own. My US-born wife and I had our AOS interview on Sept 24 2019 in Charlotte, NC. We've been married since 2003 but never had the funds to do this before. Interview went great, the I/O was wonderful, friendly and hardly asked any personal questions thanks to the length of our marriage and my wife & I having kids together. We'd taken in a 2" stack of both supporting evidence and originals/copies of docs, which he said he didn't even need to look at (he didn't even look at my passport or I-94). He also told us that our application was so thorough, he wished everyone put their cases together like ours (which is really thanks to our Attorney).

The interview lasted 15 minutes, at the end he gave us verbal approval but said his Supervisor had to give the case a 'once over', which he said will be done the following day, but no later than the end of the week (today). He then told us we can expect to receive our Green Card in 2-3 weeks. I/O ended our conversation by wishing us luck in the future and to strongly consider Naturalization when the time comes. We said we're going to and got a 'thumbs up' from him.

Question is, how normal is this lack of any documentation after verbal approval or even have my passport stamped, and is it possible to end up getting the GC without any further updates on the USCIS website? We thought we'd get some sort of stamp or letter on the day if we were approved on the spot, but to be honest were so excited we forgot to mention it to him. The last online update was August 16 when it said 'Interview was scheduled', which is annoying. We've installed a couple of apps to see whether different info comes in, but since they connect straight to the USCIS, they obviously give exactly the same info..

Timeline is:
1/23/2019 - Case received
1/23/2019 - Fingerprint fee received
6/20/2019 - Case Is Ready To Be Scheduled For An Interview
8/08/2019 - EAD Approved
8/16/2019 - EAD card received
8/16/2019 - Interview was scheduled
8/20/2019 - SS card issued
8/23/2019 - SS card received
9/24/2019 - Had interview
9/27/2019 - Online status still shows 'Interview was scheduled'