You've got some great advice. I agree with SaveTheWhales in a way that most of the time board skills are to blame for a lack of boosting height.
I took me a while to understand this, but it's always better to sacrifice a bit of board speed if it leads to better board control and an aggressive pop before take-off. If your aim is to get 10m+ jumps then you really need very strong winds (at least 25 knots) and be used to riding overpowered with excellent board control.
Look closely at every big jump video, the last few frames before take off, how much the board is pointing UPWIND. This is the ''pop'' that will give you the extra vertical height you want. The majority of intermediate riders take off with little to NO pop, with the board not pointing any further upwind than your usual direction of travel.
You can measure the quality of your ''pop'' by how high you're able to jump using the advice from SaveTheWhales, i.e. not sending the kite AT ALL. Also the more water you're able to spray off your board, the more aggressive your edging is and the higher you will go.
I'm not gonna say this is perfect by any means, but this is what my stance looks like in the last
second before take-off for a 10m-ish jump in 30 knots, flat water.

Timing is critical and difficult to achieve perfectly and consistently between each jump.
What really helps my students the most is video analysis. At some point you need to watch closely what you're doing, frame-by-frame. At your current level, it's about
small details that can make a BIG difference. But until you can visualize and understand what those small details are you may just be repeating the same mistakes over again.
Christian