Hello, I'm 5'5'' 18 y.o., and most of the guys of my age are taller than me. I want you to pay attention to Robert Downey Jr. I don't think he has complexes with his height 5'7'', it's al about charm, intelligence and charisma.
First of all stop helping anybody get better than you, stop giving your knowledge and your "secrets", this are the things what make you "you". People like to be surprised and impressed, don't worry, nobody will die if you wouldn't spread your knowledge. If you are too sincere with everybody people get bored of you, because you become too predictable.
For a long time I also was kind of an "altruistic person", I felt inside a need to tell somebody something new, interesting and useful I found, but life is to short to spend it to improve others and it is very sad watching others evolving, progressing, developing, while you remain the same.
You try to be honest and sincere with everyone to be fair, but this works against you...
A good looking, confident, calm and smart 5'5'' is always better than a stupid, arrogant and full of vanity 6'2''.
P.S. Sorry if my english is not perfect.