What the hell am I doing wrong ??

Salve,

I consider myself a total war veteran. Personally always played vanilla, and decided to try DEI and I'm absolutely in love.

However, i keep restarting my Rome campaign due to the Carthaginians.

I can beat Etruscans, i beat Epirus, in the last run i even conquered their last city to the east, and got in Greece conquering some cities for economic boosts.

Suddenly Carthage comes with 4 full stacks. They sail with a full stack navy. I get Ilyrian and Carthaginian pirates harassing me at all time..

What do i do ?

If i dont build a navy, I'll have money for bigger armies but get screwed from the back.

If i build a navy to fight 3 factions at the same time, I spend a lot, and leave the armies lacking.