6-9 is usually the sweet spot for the DS. It really moves w/o being overpowered.
2-3kt, if real, is when you drift around.
Now, in terms of overpowered, you care more about the gusts than the steady winds. Both ECMWF and NAM models show gusts in the 20s for your area tomorrow. ECMWF is usually a bit more aggressive in forecasting gusts; let's say, most of the time, if I look at actual readings from a weather station nearby I don't see gusts of that magnitude. However, like a rogue wave, I guess there could be one somewhere in the area. NAM tends to show numbers more in line (for gusts) with what I experience. Now, ECMWF may show slightly higher sustained wind some day, and sometimes that seems more correct. (But I may be sailing in places where the wind funnels; your lake: do the trees block a lot of wind?).
You should look at the water, if you see "angry" dark patches scootching over the water, those are strong gusts. You won't see whitecaps on a small lake, so hard to guess from that. If you have wind that "shakes" trees, or good parts of them, in the gust, esp. if no leaves, you may have more wind than you like. Paper or leaves being blown about is > 11 kt.
Or have someone give you an handheld anemometer for Christmas.