The best thing you could do for your economy right now is to take Harima off Mori. Oh, and don't bother with any more border fortresses, because the upgrade costs less than a shinobi.

You could try encouraging your allies to attack by leaving one of your provinces undefended. But none of your border provinces seem ideal for this.

Or try the shinobi rush: build loads of shinobi, send them to an enemy province with a very small garrison. The idea is to cause a revolt, then you can take the province, since you're not allied with the rebels. Awaji looks like a good place to try this, since you'd get access to the little island to the west of it, if it worked. (Assuming Mori's not there already)