I don't have many friends in my life either. Primary school: 1, high school: none, university: 1, at work: none.
However, I make a few real-life friends on an online game. So yeah, it is possible to make friends on the Internet.
Some reasons making friends is so difficult for me are quite obvious: I am not an attractive person, physically or mentally. I am not good at talking, not good at sensing what others think or mean.
But the biggest problem of all: I am bad at keeping relationship. There are quite some would-be-friends, but I make them all disappointed with my less-than-enthusiastic responses to their approaches.
Could that be your problem too?