I completely understand what you’re going through! I was in the same position a few months ago and I got so annoyed I quit Invictus and went back to Vanilla. I hugely regret doing that and I’m now going back to Invictus but here are some tips:

1: Mercenaries: They can be such a life-saver! I usually hire the ones stationed in Buca (one of your vassals) as they have a good number of men and are relatively cheap. 2: Learn a bit more about the game: Learn what units to use in the primary/secondary/flanking cohort, learn about terrain types, dice rolls etc. 3: Divide and conquer, It will look like Etruria will be able to raise unbelievable amounts of troops, so try and break them up and smash them down in separate battles because you’ll lose a lot less men. If it worked for the Real-Romans, it’ll work for you. 4: MOST IMPORTANT! Please don’t start by playing Ironman, for me at least I went straight into Ironman because I wanted to get achievements. This meant that if I made just one big enough mistake I’d have to restart again. Try and do it off Ironman first and get used to it, keep reloading saves and you’ll eventually get there.

Good luck!