Hi Calic. Personally, I think you could easily handle ~4CM on your femurs but definitely not any more than 5CM. There are a lot of men with femurs longer than their torsos naturally. These tend to be black men, but I've seen quite a few white men who are naturally this way too. These people don't look weird because their build is a naturally occurring body type. Look at my post in the thread "short torso and long legs" to see what I mean. You could easily pull off 4CM more because your arms are so long. I wish I had arms like yours to start out with (I'm your proportions opposite, short arms and 96cm sitting height). If you didn't have those long arms, you'd look like you were walking on stilts, but your arms make everything come together nicely, and make you look like a naturally long-legged person. I think your LL actually made you look younger (and, of course, taller), because it have you a slimmer profile, since you haven't gotten any wider.
I am biased, after having looked at so many proportions threads, but I think that, currently, your tibias do look just a little too long. I don't think anyone would casually notice, especially while you're wearing pants, but I do think that just a tad more length on the femurs may make your legs look a bit more natural. I don't think that 4 CM on the femur will affect the way your upper body is perceived, but please don't do more than 5CM, jut because, at that point, your hands won't be close enough to your knees to appear natural. But, you could also stay the way you are currently and go through the rest of your life without worrying about being short or having to do another LL. Some people, like Ryan Gossing, have long tibias naturally. These people are rare, but they do exist.
Are you sure you did 6.5CM on your tibs, or is it possible that you may have done a bit more? How did Dr. Sarin measure your final distance? I've often heard that measuring based on X-rays alone is unreliable because it's hard to tell where the bone gaps begin and end.
Anyways, I hope that helps you in some way,
Tall