Who here has been single all their life.

（´Д｀;;) i get really nervous around girls for some reason, especially when i like them. Is it game over for me?

I'm right now sitting next to a girl I like. I like her alot. But the thing is I feel nervous when I'm alone with her, so I can barely talk to her. I'm not sure, but I get a feeling that she maybe knows that I like her, or I'm maybe I'm tricking myself. For the most of the time when I spend time with her and my other friends,I'm quite silent and don't joke very much as her and my friends.
I belive the others see me as a stiff person. I'm ok with that, but i don't want to be considerd that all the time.
Btw she's five years older than me.
I also sometimes really don't belive that I have any chance on her, but I try not to be that negetive.
I sometimes feel VERY lonely, and imagine sometimes that
something bad would happend so that I would be forced to confess to her.
I'm probably to immature for her.