>inland map, indy 6, otherwise standard, around 12 impossible AI
That's just about as hard as you can make this game. No shame in having trouble with that setting. It's very crowded. It's almost certain that this setting will lead you to close contact with multiple impossible AI's very early.
>Typically, I would get around 20 provinces by turn 15-17
That's pretty good considering the size of the map. You have more than your share and are squeezing your neighbors.
Part of the issue with this set-up is that it requires lightning fast play. You need not only to take many provinces... you need to conquer a neighbor early. Absorbing a neighbor early and being ready for more is hard. You will need to defeat that first enemy with great efficiency, taking almost no losses. If you expand slow, or take losses, you won't be in shape to handle the others.
Jotunheim is not a fast nation as many troops need lots of production. Furthermore it is hard to stock up border patrols/response teams with these pricey troops while also attacking enemies successfully. As I said... you have chosen a hard scenario.
I don't know which theme you are using, so I'll toss advice for each;
First, as the other gentleman suggested, consider enchantment-1 and using your death gems for reanimations. Those undead will do just fine.
Joutunheim [Iron Woods] relies on stealth, blood, and random magics. None of this is fast, and won't help much in your situation. It's a very poor choice for this scenario. I'd advise skipping this theme. If you must use it, use a pretender that can handle combat, and use mercs as much as possible. Pick a slow developing enemy and try to target your troops for a fast kill. Hurlers work well versus small numbers of high armor troops such as Ulm is likely to have. Javelinists work well versus light troops like Mictlan or C'tis are likely to have. Good luck!
Jotunheim [Utgard] has some extra options. You have Huskarls that are Ok low resource troops. They are good to mass versus lightly armored enemies. The Norna using enhcantment-3 can cast Raise Skeletons. This is a great battlefield summons. A bunch of Norna cranking skels can often overwhelm enemy forces and take no effective damage. The Seithkona mages can take advantage of high magic scale as they do good research for such a low cost mage. Furthermore they can cast eagle eye followed by Nether Darts. While this takes some serious research, it's a very potent spell combo. A stack of mages summoning skels as a screen, while others flick nether darts, can blow out substancial armies. Norna also have access to Paralyze, which is another really good spell.
Jotunheim [Niefelhiem] must use the blessable giants in order to get speed. I suggest a Green Dragon pretender with nature-9. Getting beserk onto the giants is clutch in order to prevent morale issues, and regeneration helps keep these big boys alive. A handful of such giants can crack independent provinces. As long as you don't take a bad loss, these giants can be efficient.
Well, that's my advice, for what's it's worth. Good luck.
