Hi 2dumb2live,
45kg? You must either be a small and skinny boy, or a small chick. Either way, at 45 kilos, almost everything in the size you need is going to be built for high winds for riders weighing in the 70-80 kilo range. This usually means you are going to be buying a heavily reinforced high wind kite which will be very heavy, and not be happy flying in less than around 15 knots.
Most (not all) small kites back stall and luff in very light winds and also become hard to relaunch.
15-22 knots is a fair old wind range and we had a young fella riding for us , about the same weight when he started and he used a 7m and 5m for that wind range.
The Ozone Catalyst is built light and not as powerful as a lot of other kites so it works super well for light riders in the lighter winds. Being small, you will also no doubt have shortish arm reach which rules out many of the previously mentioned kites. The Catalyst has a short bar throw and light bar pressure so all in all, it would be the most ideal kite for you for the conditions you mention. If I wcould think of a better suited kite, I'd mention it, but the Cats are the cream of the crop for smaller riders and women learning.
Good luck sorting through the BS!

DM