It's Per that is asking about the IS 144 and I don't know if he is racing or not.
My 111 has essentially the same volume as my bump and jump, but its width and design allows it to carry a much larger sail. My 105 board doesn't sail well with anything larger than my 6.5. My 7.5 is out of balance on the board.
For your weight, I can't say if the 122 will plane or not with an 8.5 in 16 to 18 knots. Maybe Remi can help with this question. However, I would think that the 133 should plane in those conditions, especially if you have good pumping skills.
A 6.5 on the 122 should work if you have enough wind (25-30 knots). I used a 5.8 on my 111 a couple of times with no problem (22+ knots).
You might consider the Futura if you are not slalom racing. They are probably a bit more user friendly for freesailing, but will be slower to plane because they are narrower in the tail.