There are only two ways to increase FOC. Add weight to the front of the arrow ot take weight off the back. So, switch from vanes to 4" feathers to take weight off the back. To add weight up front, put brass washers between the broadhead and insert. Be carefull with adding the weight up front because it can force you into a different spine class arrow. Experiment with it.

Don't know if you'll be able to reach 12%, but you'll get at least 10%.