As others has said - just take your time, it is not easy.
A few hints:
Learn to twist your body, leaning in like on a surfboard does not work at all, the turning impulse has to come from your body "yawing" - and then you lean to follow the curve.
As one said, learn to make S turns as sharp as possible - as your major problem with turning, besides kite coordination, is you will make a huuuuuge wide arc and everything will go wrong.
DONT turn the kite first and follow - does not work and you will end up with slack lines and a kite that drops.
Bear upwind first, a lot, keep the kite at 45 degree.
Use longer lines, everything get easier with 25-27 meter lines.
Fly the kite up slowly, and turn the board around now simultaneously.
This is key, and with time you will learn to get turning all the way to toeside, and still having a bit of pull in the kite.
Thats all there is to it - but it is NOT easy, so just keep trying