At 3-4 bft, there are no whitecaps, less than 10 knots. While you can plane, it will take good pumping skills and a steady wind to stay on plane. Some up and down wind sailing is possible, but no significant angles.
I have a F160 and an 11.0 as my largest sail and I weigh 80 kg. I sail on lakes with variable winds and don't go out under 10 knots. Too many holes = falling off plane too often.
You could go for a large sail (11.5 or 12), but it won't make a significant difference. If your wind is at 3-4 bft most of the time, something larger than an 11.0 may be the call. However, the 11.0 has a much better top end range, plus that range will depend on your skill development.