Your "problem" is very normal so to speak.
First off, you are still new into foiling, so handling kites in winds around and below 10 knots is something you have to learn.
Also, use longer lines as Grigorib correctly adviced you.
Secondly, you are not alone, for the average weight experienced foiler, a 10 m2 can go down to 8-9 knots, on todays medium to bigger wings.
But you also need a light kite in this wind.
So a "more normal" 12 m2 is too big and clumsy and heavy to hang in winds around 7 to 9 knots, where it could be used once you keep it up.
In fact a 10 m2 same weight is just as easy to keep flying, and usually got the same powerspike.
This is why most dont have a normal 12 m2, as it will not work well or at all in these winds, so many stick to something around a 10 m2 which works fine in 9-11 knots no problems dont even have to be superlight, just not too normal heavy.
And as you want few kites I somewhat understand, you will ride your 12 m2 in quite high winds too I presume, thus a strutless or onestrut might not be the best choice.
As otherwise, if you want the best LEI for the job, you should use a superlight 12 m2 for 7-8 knots, light 10 m2 for 8-9 knots, and then you can use your normal kites 9 m2 and smaller for 10 knots and up, in 10 knots EVERYTHING can fly easy.
Maybe not relaunch, but should not matter when experienced
Only in marginal winds below 7 knots, you need a light foilkite, even a normal foilkite is totally useless in this wind.
Strutless kites are perfect for light wind, but if you only want few kites to cover a higher range, you need strut(s), to avoid the flapping.
As simple as that.
And having one or more struts, AND being a light kite, limits your choices extremely, so you either have to find these and maybe even pay a bit more, or use other kites and dont ride in wind below 10 knots.
Having said all of above, you should consider the winds to be the "lower ends" that some of us like.
Others ride in much more wind for their personal sweetspots, with the same kitesizes (if same weights).
And beginners usually the first two years when learning, also ride with bigger kites in this period.
Peter