Honestly, I'm a little bummed out.

I first joined a Faction, conquered with them, but eventually the Daimyo stopped making wars. No other clans joined, either, so I guess it was a reasonable decision, but also boring.

So I split off and founded my own Kingdom, went to war, conquered, and...couldn't get anyone to switch sides to me, no matter how unloyal they were or how good my relations with them. So I had to consider either of the following two options:

1) Conquer all of Japan with only my own clan, which is doable but also extremely grindy, repetetive and un-fun.
2) Stop playing because ♥♥♥♥ that.

For now, I chose 2).

Not going to lie once I conquer all of Japan I never want to play it again

At some point, no matter the mod, the game always ends up being like this if you want to conquer the whole map, same with warband, its just endless taking castles, defending, til the map is yours.
I always either take a break from the game long before i conquer the map, or start a new playthrough, since the mid game portion of the game is the most fun for me.