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 know I'm making this a bigger issue than it is.
The thing is that I'm just not sure if I could cope with her, because she is quite lively, and I'm often calm. It's not that I don't like her lively mood, but it's hard for me to be as enthusiastic as she and rest of my friends.
I ain't maybe ready for a girlfriend.
I'm maybe too immature, to realize my potential to be her boyfriend.
I would REALLY like to know what she thinks of me, but I feel it's too personal to ask her that. But I realize it's my only chance to find out.
I also have to mention that I earlier made a girl upset for writing a strange letter to her,(but that's another story), so I'm really not sure what to do.
Since I've got no experience with girls as friends or girlfriends. I'm don't know if I should talk to her or try something else.
I don't dare to ask her personal matters, like how she is feeling, because I don't really get the chance to ask her that. I usally see her when other people are around, and I don't want to disgrace her in front of her friends.
I wish I could be with her in a desolate place, where nobody could overhear us while talking.
Yes I know I'm a coward, but I don't want to do stupid mistakes or upset her.