ok first, for Lumia 920,
There are 3 updates,
1.Amber +GDR2(ONLY FOR NOKIA Phones(others just get GDR2))
2.Black+GDR3(ONLY FOR NOKIA Phones(others just get GDR3))
3.Windowsphone 8.1
So if it says Amber On a Nokia Lumia 920 phone, that means you have both GDR2 & Amber
so Amber which is also called GDR2 is now Live (meaning you can download it)...If you are not sure what Update you have, then go to settings =>About => and you will See "AMBER" in your screen, If it says AMBER, YOU ARE UP TO DATE

If it doesnt say, Then please post a Screenshoot so we can c it.(ALSO Go to Music+Video and when you c the collection, you should be able to c a option called "RADIO"... This only comes if you have AMBER(GDR2) Update
now as your furthur Knowdledge ,
GDR 3 update is still in Developer Mode(which means General people can't still get it, but you can create a Developer Account and get it) .. That Update will soon come to your phone(before January 31,2014) as a General Update for everyone
Then after that update, Another Big Update will come and thats called "WindowsPhone8.1" (it will in middle of 2014 i think).
So, Again 8.1 is NOT AMBER, AMBER and 8.1 are TWO DIFFERENT updates

and as for your questions, The only update you can have in your phone is AMBER... so check that out..( You cant get GDR3 or 8.1 now)