Did you finish off everything in Broken valley and on Sentinel Island before getting your dragon form?
Have you explored the tower, opened all the chests and mindread your servants, etc?
You can teleport to the outside shrine on Sentinel island, jump up the nearby rocks and run over until there are no overhanging branches, so you can transform into a dragon. There should be a few remaining opponents, and there is a book in a boat in a tree you can get for what's his name (though you may want to read the book yourself, rather than compete the quest, and just not bother talking to the guy again).
In the fjords the opponents along the mountain trail are level 17 or 18 (or were in D2:ED) and at level 20 you should be able to clear down the trail, cross over to the nearby beach and swim or fly over to the beach behind the anti-dragon shields (possibly removed in DKS) where there are a few more Black Ring soldiers. The path with the level 21 imps should not be too difficult, especially if you summon your creature for support, and there is a mine there you can explore before having to get to the bunker to deactivate the barrier.
I have not played DKS yet, so I'm not sure how the changes to opponent placing in the fjords was done, or if the anti-dragon shields around the bunker were removed.
Welcome to the forum.