I've learned formula sailing with a 3-cam 9.5m2 freerace sail.
It was a relatively light sail and good to learn, but I don't use it any longer.
The problem with these light wind early planing sails is that they quickly get overpowered when the wind picks up.
I've found that I can hold my 11m2 4-cam pure formula race sail as long or even longer than the 9.5m2 freeracer. It's just a lot heavier to carry to the water and it's a pain to uphaul it when it's in the water. Luckily I'm at a stage where I rarely drop the sail into the water
Because you're much lighter than me, probably the size of +/- 10m2 is really good for you. But think twice about the type of sail. The pure race/formula sails, with their extra stability and control, will give you more fun in the long run.
From my point of view, pure race sails are NOT more technical nor difficult, ONLY easier and more comfortable when sailing, BUT unfortunately also heavier to carry and uphaul.
PS: I'm also no competition racer. Just a recreational fun cruiser.