As a Lithium devotee I'll chime in. I agree with eppo ;) I weigh in at a whopping 72 kg (158 lbs here in the states) and own 12m & 9 m 2013 Lithiums. It was also suggested by a shop owner that the Lithium's on the well powered end of their range are more of big boy's (or girl's) kite.
This all said I have one personal caveat about the Lithiums...There's just something about the way they feel; refined, performance, etc. I don't know but I don't mind there not being ideal for lighter weight riders.
My story:
The 12 m is my go to light wind kite on a surfboard starting at as little as 12 knots; although, in flat water conditions I've managed to have a great time right up to 22 knots on the same kite on a twintip. It was a stretch, but that's the thing on Lithium, it's a well behaved kite even when it's at the top of it's range. This being said for the upper end, it will pull hard and you'll find yourself sheeting out all the way - much in the way I would luff out a sail on my sailboat - but it's always under control. And if the wind backs off, you're back in business again. Compared to my previous kite, a 12 meter Cabrinha Switchblade, it has a knot or two less upper wind range.
As for the 9 meter Lithium, I can get going beginning in middle teens to start and I'm good until the mid twenties (knots). Beyond this I'm ready for my smaller kite. Your being 7 kg's lighter, I imagine the 9 would get you going in the mid teens no problem but will top out in the low twenties. You're blessed to be 65kg ;) I'm also relatively light and I've learned (intuitively) to make the Lithium work without it becoming a handful. It's just that kind of a kite; easy to figure out, plug n play, but NOT boring. This is what I mean about being intuitive. After demoing a series of fine kites, there's just something about the feel of this kite that makes up for its slightly smaller range on the high end.
I demoed a 9 meter Cabrinha Vector and it's a nice kite, but just not as dynamic as the Lithium (Vector doesn't have the power and slower in the turns, and the top end really isn't much better either). I used to own Cabrinha Switchblades (cut my teeth on those), ok but I'm not into wakestyle and they don't pivot turn well and are slow turning through the window by comparison. The North Rebels (Fuse - the 4 line version; both are winners in my book) are very refined and has a better range than the Lithiums especially lighter riders. I like the North's, but, but, it just didn't have that Airush feel. It's hard to explain and needs to be experienced.
I recently sold my high wind kite, a 7 meter Cabrinha Vector (nice but too sedate for my tastes). After consulting with Eppo and Mike Birt (aka product guru) I purchased the "higher aspect" Airush Varial 6 meter. There was little chance of demoing it or a smaller Lithium so I took the plunge and decided to air on the side of high aspect kites for winds over 22 knots. This being said, there are slews of smaller riders on little Lithiums that are perfectly happy with them. I'll probably post my experience on the Varial when the time arrives.
It's a personal thing. My point is to give you a perspective, albeit biased given my intermediate kiting skills and what I ride (surfboards / twin tips in small waves and open ocean swell). While you probably wouldn't be unhappy with any choice, they're are so many fine kites out there, you're best option is to DEMO a kite if you can. Ours are opinions, and while they have merit, they are biased and colored in my case through - Airush colored lenses. Btw, I'm not a team rider, etc., for Airush. Just an admirer of fine products.