DeanRobi I understand all kites fly differently and at the 18-23knot range, your Woo height meter sounds about right +-...
For the 'stronger' winds you may have to pay more attention to fine trimming of the kite at full power, as everything is happening within a second. There is obviously a difference in trim between 20-25-30knots, backstall is the height enemy here, we get all excited about the jump

but are killing the kite
Trim the kite for max wind speed on the water - your jumping not Lawn Mowing...
At max speed, Just before you jump
let the bar out just enough so the kite will fly forward to the edge of the window (while maintaining its shape and line tension - a big kite will produce a lot of natural wind drag at high winds, trying to pull it downwards and back)
The steering will become lighter for that few seconds
This will also let you initiate the load and pop solving the "find it too hard to edge and aggressively drive the kite up" problem..
Then slam that bar in, your trim will give you better lift..
Try jumping into the wind a little more to avoid the floaty flat jumps
For the 8 and 12, learn how to heli loop just before landing - it takes the meteorite impact out of it
0r steer the kite backward and dive it hard forward just before landing to create lift for that buttersoft style.
Your weights not an issue - my friend Robin from The Pond, goes huge on a 10m at around 110 kg ?
SammyJay Over the Handle bars hey :) we all remember that stuff. Try some of the above..
Also a good exercise, that I always do at the beginning of a session - is the Max speed Load n Pop with the kite at 45 degrees.
It helps to get into the co-ordination groove again - play with the line tension and board angles BUT keep the kite still.
It will help you find that sweet spot again
Guess what happens when you add the kite to it
Let us know how you all get on