My only campaign as the Saba ended after 4 turns when I lost my first battle (i'm that good!) so I have no real advice, although as the Seleucids I had a similar problem, my solution was a naval invasion of the Nile Delta whilst the Ptolemoi were distracted in the Levant, it worked wonders.

In the meantime I will give offerings to Belenos and Teutatis to bless you, I will dedicate the offerings by making breakfast and then eating it.