To End All Wars uses a different command structure than most other AGEOD games, so if you are bringing that experience to this game this may be one source of confusion.
Pause your battle for the moment and do this things, find a 3 star general within command range of your commander-in-chief (GCHQ) who is not an army commander and give this leader army command. Next, stack as many units into this army as you can with not incurring command penalties. Try the same this time by putting corps units into the army. You will send there are several decent army formations.
Corps are built typically with two regular infantry and one artillery unit. That is pretty much the maximum size, except you can usually add one smaller unit like a raised conscript division. These corps will act together as long as they are in the same region or a region adjacent to an army.
So this is a 'big' unit. An army with several corps units in the same region, but not inside the army. They will all join in battle together with the army's lead.
Naval strategy for me as France has the fleet helping the army attack Greece or the Ottomans, but the naval blockade in the Atlantic and the Med is useful.
What you are building sounds about right. I am a natural born attacker, so in this game I have to be careful to suspend the offensive before my losses go so high my NM is hurt. Probably against AI attacking is the most interesting thing to do. If you pbem as France, you initially need a great defense.
These games take time. If you have the expansion Breaking the Deadlock, some of the smaller scenarios are better for learning the game.
Yours will soon become a mad infatuation once you understand the underlying conceptions a bit more.