at your weight the 111 (if right finned -42,40,38-) has a wind range 12/13-30 knt.
Of course it will happen that in 13 knt someone with a bigger board will replace better than you,that will better survive in a wind hole or it can happens that someone will stay cooler than you with 25+ knt because a smaller board BUT it's hard find a board with a similar broad range.You can even charge it with a 8,4 but,I guess,only if your goal is make some more speed in flat water and steady wind.It won't make difference (with a 7,8) for planning ability indeed.Plus you can go with a 6,1 but the 6,7 is the smallest I suggest you.Don't worry with that combination (and the right fin) you can afford a big wind.
I've used this board since 2007 and I'll buy it once more in 2010...
If you're searching for a real light wind weapon take the 133/131.At your weight the 122 won't make a real difference with the 111 in light air (trust me!).