I think ididUrMIM is correct. I wouldn't upload any photos on here but I dont think you should ask family advice. They may be scared or find this surgery ridicouls so they tell you a smaller amount than you could go for. You and your doctor will determine this as you go. you may want 8cm but find 7.6cm is perfect for you. You dont know until you do LL unfortnanetly. Thats why so many answers change before and after they had LL
sitting height really is NOT relevant
for schatten if you are worry about your shoulders adding 8cm honestly isnt going to make a difference. When you get LL your legs will barely have muscle to them at first. They'll be thin and trying just to walk normal will be your goal and your shoulders will look even wider. if you dont want to lose it assuming you remuscled your legs, i still think theyll in proportion but if you feel your shoulders could be widers theres some opitons.
1. Go to the gym and start lifting to widen your upper body.
2. Add implants to your delts to give illusion to broader shoulders
3. Fat transfer from other parts of body to shoulders (this is common among body builders-only go for top plastic surgery for this)
There is no average skull/arm/leg/shoulder size for 188 or 190cm, it differs between races, countries and you can have 4 people of 190cm with different proportions and look completly different. Youre assuming most hit golden ratio
Trying to be like everyone else wont work, you have to be the most proportined you