Divide the race into 4-3 mile segments. You are attempting to run 6:53 pace so that would be 1:22:26 for 12 miles. Multiply that by 50.5% and that is what your 6 mile split should be. (41:38) Multiply that again by 50.5% and that is your 3 mile split. (21:02)
Miles 6-9 should be run at the same pace as 3-6 which is 20:36. When you subtract 41:38 from 1:22:26, you are left with 40:48 for miles 6-12. Subtract out the 20:36 and that leaves 20:12 for miles 9-12.
I consider the halfway point of the half marathon to be 8 miles. You don't want to be "racing" until after that.
At this point your splits will look like this for the first 12 miles.
7:05
7:00
6:57
6:52
6:52
6:52
6:52
6:52
6:52
6:45
6:45
6:42
You should have enough left to go all out and run 6:30 pace to the finish and be comfortably under 1:30.