Was this an indoor 800m, and can I ask what part of the world you're in?
The 3rd 200m of the 800m is a challenge to master!
Most people can get the opening 400m dialed in right, and the last 200m is flat-out almost no matter how you run the race. But from 400-600m it is very easily to keep running 'fast' off of the first lap, but actually degrade a fair bit in speed. Whereas 100m-400m should feel fairly even in effort, the 3rd 'section' should definitely be a rapidly escalating effort -- if not, you are giving time away
As others have said, perhaps more than other distances this is something you can really only get right for your own physiology with repeated races. It's not a coincidence that experienced coaches/runners are all saying to do 600m TTs and/or a few more races!
In short, with your apparent endurance as shown in those 3:10 1000s, you seem to have more than enough speed to run a 2:12 or even sub-2:10.
Good luck, and HAVE FUN! Let us know how it goes.