Can't say I'm familiar with that archetype...
It looks like your options here are:
1: Two-Weapon Grace
2: Three levels of Unchained Rogue
3: The agile weapon property
or 4: Ditching the shield.
I personally recommend 4, but you do you. Also, just to make sure: that is a darkwood shield, right? Because you take your shield's armor check penalty as a penalty to attack rolls with Weapon Finesse.
