What's wrong with my friend?

[ceiling.down]

Backstory: I am the most asocial person I have personally ever met. I have one friend, not including this one. I kind of didn't mind until this year, honestly. Things are different now and I wonder what's wrong with me.

Then I've made a new friend just like I wanted to.She had just transfered and came to my lunch table. We have nothing to talk about. She's a really boring person, I have no calmer way to put it. I just can't do it. She talks kind of strangely, I stand behind my accusation of something being not all there. It doesn't matter but it doesn't improve the situation. She phases out so much and seems to simply lack.. thoughts. She's like a blank slate. She just never appears to be really thinking, like a dead fish. She smiles a lot, but it doesn't seem like she's enjoying actual funny stimuli, as if she simply learned to laugh randomly at nothing at all really. She laughs at not really funny things but not at my bits of sarcasm. Like she doesn't get it. [cont]
I asked her if she thought it was possible that nobody really exists and she said no, and I asked for her thoughts on it, and she thought for a while and then she got distracted and said something else. I tried a few times to talk about the universe and I came up blank. She just then randomly says how she wants to dance because the school play is coming up. Yeah but..she doesn't seem to say anything with any thought, just facts, like her favorite color or schedule or events or clubs, like a book. She has no depth! HELP ME. I miss my alone time with my imaginary friend and my occasional interactions with real people that I found so exciting. Now people think I don't need any mental probing for I have a friend so I must be fine. I want to get away! But I worry if she's really "mentally retarded" in some shape or form, then it's cruel. But people talk to her and she says she has friends. HOW. More friends than me at least. WHY. I don't think it's what I don't have, but what I DO.
I AM SORRY it's long but please don't come just to whine about that. I'm doing my best.