Hi Sabs, I'm sorry you lost your board and I hope you find it.
I was happy to see another kiter was out there looking out for you when you started swimming what looked like more than 1km back to the shore. I waited 30 minutes after finishing my last lesson to make sure you were back to land safely.
I just wrote a post in the newbie section which probably applies to your situation:
www.seabreeze.com.au/forums/Kitesurfing/Newbies-Tips-Tricks/Are-you-ready-for-deep-water/Christian