After you finish the game I thought you were able to return to the outside map and finish
some quests. I finished the game and was sent back to the load game screen.

Has anybody else had this problem or is this normal? I have all the current patches for the game.

Only way is to cheat. You can use the console cheat. You can find it at www.bgdungeon.com. I got all the tears, opened the door , saved and then warped to my stronghold.