20 years old is super young. I tend to disagree with anyone this age doing LL because of two reasons: they generally learned about LL in the internet and decide to use all their life savings so far to do externals tibias in a developing country (those who have no plans of going through higher education), or they're putting their higher education at risk by doing LL, if currently engrossed at university/college. Also, you can go to a psychiatrist for drugs if you don't believe a psychologist can help (should probably try before, though). They can soften those feelings.
I also think you should listen to the advice of veteran LLers like Body Builder if you're really going to do this. If external femurs has a bigger complication rate (besides just being very difficult), then that is a problem, and you should consider external tibias instead. You need to be able to go back to your normal life afterwards. I don't really know because I have never deeply researched anything but fully external tibias (I find LATN/LON riskier) and internal femurs.
25 is also young, by the way; you're probably just too young yourself to see that. You still have your whole adult life ahead of you at 25. If you do it by then, you'll have your education completed, at the best university in the country no less, and it will probably be easier to deal with a longer recovery than expected, if that ends up happening. However, I don't know you or your situation personally. I'm just giving advice to the best of my ability.
My situation is totally different. I mean people around me sometimes make joke about my height and there is nothing i can do in order to avoid it. I can go to psychologist, and i may feel better. But it will not change people's opinion about my shortness. My legs hurt tooo much when I wear insole. And once i tried not to use insoles,but one of my friend said that it seems like you become shorter. I understand what you are saying, you are right I am young to do this surgery. But i don't wanna live the best part of my life (20 th) with short height. I will never be able to live these moments of my life. I don't like taking risks but there is no option left for me. So far I have tried many ways to increase my height but none of them worked unfortunately. You can't even imagine how many conflicts have I ever had with my parents because of myf shortness. I have always accused of them because of my genetics but while deep down i know that it is not their blame, it is just the unjustice of life against me. My peers enjoy their tall or normal height and it makes me feel jealous. Why i should be embarrassed of my height? It is just unjustice!!
And in terms of external femur, I will talk to my surgeon before surgery, I have talked to his patients who have done external femur and actually I am just confused. Anyway, it is better to talk to his patients face to face before surgery to make final decision