What to do???

I checked back in with Vivec and he mentioned that there was still much to be done. But I inadvertently did a looooot of adventuring "on the side" before continuing on with the main quest at one point. (Didn't know how to continue with the MQ at that time, so I went adventuring.) So, I'm getting impatient. Not up to much "poking around to see what I find" any more 'cause I feel like I've been there and done that all too many times already. I'd much prefer someone just coming right out and saying, "Do this, then do that specifically", etc.

Help?

Well, the game doesn't have a definitive ending. If you've defeated Dagoth Ur, then that's it, you're done the main quest. There's a crapload of other things to do, there's the various guilds and political houses, Daedric shrine quests, and of course the two major expansions, Bloodmoon and Tribunal. Each has its own main questline and even more side things to do in the new locations they add.

The good thing about Morrowind, Oblivion, and Skyrim is that you can keep on playing as much as you like even if and when you finish the main quest. You can quit at any time that you're satisfied with your accomplishments.

Tribunal and Bloodmoon.