Really - Your trouble is 15 - 18 knots on a 10m kite. Harden up princess.

Dropped 2m in kite size and you wonder why you can't jump as high. You serious!!

Take that 10m out in 25 knots and see what happens!

10m in 15-18 sucks balls unless your on a hydrofoil.

Mate, It's all about technique. Pay attention to the good riders next time you are at the beach. You will notice they ride with a lot more speed than the other kiters. As weebitbreezy commented, you need to improve your stance and edging skills so you can ride fast and in control. This makes a huge difference when loading up and sending the kite for a boost. Most beginners ride with too much back foot pressure which slows you down. (Especially in light wind) Try shifting your weight a bit forward so you have the full length of the board edge working and lean back against the kite as you gain speed. I'm no expert but give it a try. For your weight, kite size and board size, you should still be able to get a reasonable amount of air if you technique is good.

NorthernKitesAUS said..
I don't think his technique is bad, after all he did say he could "boost" on a 12m fine. Actual meaning of the term "boost" can be a personal experience! But yeah... 15knots is not boosting wind. 25+ knots, then you're talking mate! And on a 12m, even better! Just make sure it's a fast spinning kite so you can loop it and land safely.

Oh yeah? What 12m kite do you ride that is comfortable in 25+ knots? You'll need some seriously good technique not to get pulled off your edge sending your kite in those conditions.
Ignore his 'chat'. Big kites in strong winds put you at risk of being 'that' guy. We have one at our beach. Biggest kite out there (small dude too), hogs the flat water and rarely goes high enough for his board leash (yeah on a twin tip) to leave the water.

Different boards can help. Something with flexible tips will make it easier to keep a good edge. Lots of rocker can make the board slower and more power hungry. Wider boards will help you get the speed but make keeping the edge more difficult - probably thing of shifting your normal wind range down by 3 knots or so (top end and bottom end) but if you are nicely powered you shouldn't really need bigger. Bigger fins can help though - can be a cheap way to getting more line tension and more height. But assuming a modern freeride board, you probably have what you need really.

How do you know you have a good strong stance? When you are edging hard with the kite low, the bar should be just about touching your front knee and the spray from your board should be almost hitting the lower lines of your kite. Your board edge should be fully engaged so your front fin is just about in the water. Easier to practice on flat water but the same stance works in chop too - though you'll use it more to accelerate into a boost rather than hold it whilst cruising around.

I ain't the best booster out there, but as I'm still improving my technique the bits I needed to sort out are still fresh in my head - take whatever works for you but the caveat is that there'll be a load of stuff I haven't worked out for myself yet.

Edit: Sorry if this seems a bit abrupt with NorthKitesAUS but I find it difficult to believe someone whose technique is sorted is going to be asking questions in the Newbie forum. Lets make it helpful not just a variation of Jeremy Clarksons catchphrase - 'More POWER!'

10m is no good on a twin tip in less then 23knots to me at a hefty90kg with wet suit soaked. Weigh yourself wet. don't count it as when your naked scaring your self in the mirror. in such light winds don't bother working on jump height but perfect your edging and timing of sending the kite till your confident in its position even with your eyes closed. Work in back roll kite looos in that least you won't be smoked landing them. If U want big air try a rebel or an evo 9m in 30 plus knots. They are the good days !!!