I would agree, for 10-16 mph you chose a sail that is really too small for a 75 Kg. ( 165.3 lbs.) sailor on a Rio S.
The 5.5 m2 Tush Storm will be what you need, at around 20-22 knots, but by then the Rio S will be getting a little too big for the conditions.
For 12-16 mph a 6.5 -7.5 m2 rig will be what it takes to get planing at your weight.
You've also purchased a fairly heavy 45% carbon mast. It will be durable, that's for sure, but for free ride
sailing, anything < 75% is overkill on durability, and you will really feel the added weight.
From the Tushingham line up, a 7.5 T4 with a 460 cm Carbon 75 mast would be my suggestion.
You also probably need a longer boom as well.
You will be able to use your existing 5.5 Storm, FreeWave 45 mast, and boom when you get wind conditions in the 18-22 knot range (20.7-25.3 miles/hr).
Ultimately you will want about 3 sails for the 10-20 knot range.
You have the 5.5, add a 6.5-7.0 m2 and later get an 8.5 m2 for windspeeds < 13 mph.
Hope this helps,