Hi, sorry for the late reply, was on the road...
Well what freestyle board is it, what fin came with it??
6.9 is a big sail, i would say it should work with 26cm but you have to get used to that...
If the 26 didn't work well for you, you should maybe go for 28 or 30 cm... a freemove fin should work for that kind of sailing.
What is your body weight? - if you go on 6.9 and 110 L in 5bft, you must be pretty heavy??
let me know
good winds
Rossi