I would not pick a Formula at all... You say you are "progressing to planing", meaning that you are in a learning phase. At your weight, in order to get planing early on a formula, you would need a 12 m2 sail. That is BIG and really requires some technique to muscle around.
I would rather recommend a big Futura, or some other freeride board in the 150-160 liter range. A 9 m2 sail is already fairly powerful, but the handling is still reasonable. If you have to go bigger than that with the sail depends on how light the winds are at your home spot. Besides, you need a powerful freeride sail rather than a 10 m2 formula highwind sail.