Go for the 8-12m the 10 m would strugle a bit under 14kts with just the one board. But for maximum windrange the 14-9 would suit from 9 to 34 kts, the 14m is a light wind machine turns quick and will have you ridding frestyle moves in 12kts. The kites always feel like they are well powered up but you always seem to get a bit more depower out of them than what you would think.
Your lucky at your weight as most wind range charts are for people that weigth 75kgs. So jump on the f one site and check out the chart to see what they recomend for min-max range
www.f-one.world/The actual differance in bottom end between the 12-10m isnt that much on paper they will both get you ridding but depending on what style of riding you are doing te 12m will power up sooner for jumping etc, but the 10m would be better in the surf with its faster turning in the bottom of there windranges.
good to see more dos riders out there