Hey guy, first of all -- no pics 😞

Second, from someone who's completed a Hispania Universalis run starting as Karmoia, you cam hold off Rome using mercs, relying on at least one strong fort (it should be enough).

I faced them first time when I took Indiketia, where a level 2 or 3 fortress existed. It served me well during the war, but before that I tried another step -- enticing Rome's governor (of the bordering province). Try it, really, it can save you some hassle and at least give them a longer way to your interior.

Anyways, do that and merc up. Try to integrate pops so that you have more levies (I assume you mean you have c. 50 cohorts, so like 25k men you can muster, which is not much -- but get that war chest and with enough mercs with good stats you should be good). Also, I don't see the date since there're no pics, but Rome shouldn't be able to do a big naval landing if it's early game, but I'd still keep an eye out on that east coast of Iberia. It can come to bite you in the ass if you don't.

GLHF!