How do I know if my child has Asperger's?

I have a five-year old daughter who is in kindergarten.

I've read some of the Asperger's "checklists" and I'm confused. Some of these
items she has in spades; others not so much.

However, it feels as if something is off.

She is one of the youngest children in her kindergarten class, and her teacher has
told us that she is incredibly immature--and not as mature as the other kids in her
class. She is a sweet, compassionate and very sensitive little girl. She's funny
and she's fun to be around.

However, she has problems with boundaries. She will be silly when she's not supposed
to be, and she doesn't seem to respect or understand personal boundaries. She seems
perplexed, in a very innocent, endearing way--about why people are mean or call her names.
She is not invited over for play dates or birthday parties and she's said that other kids
are telling her that she's weird or stupid. I know she feels terrible and just wants
friends.

As far as her intelligence, she's picking up things in kindergarten and starting to read.
She comes home and tells me what the teacher said that day--verbatim. She's average
academically, but I've noticed that she's incredibly impatient when it comes to learning.
She doesn't want to go through the work to learn. She's interested and she wants to get it.
The fact that she doesn't know it all now--frustrates her.

I don't know if what I wrote is helpful. I just thought I would give some background.

Does anyone know what the telltale Asperger's signs are for children as young as 5? Sometimes
I don't know if she has this, or if she is just being a typical kindergartner with a somewhat
immature personality.

Thank you for any insight! :)

my son could spent all day in the pursuit of information on bees even at 5.

He loved legos and could put together lego systems that adults would have trouble with, and if even one block was off, he would tear the structure apart and start over again. It was not unusual for him to spend 4-6 hours on something he was highly interested in.

At 5 he didn't know his classmates and didn't even say hi to kids if they said "hi" to him...and meanwhile the kids were very friendly with him. He would only talk about topics he was interested in and would give you the entire reference on Bees, Wasps..etc

He was very formal and in fact was more comfortable with adults than kids, he just couldn't figure out how to "make friends" and therefore didn't. If anything, kids with Asperger's can appear on the surface to be far more mature than their years (but not always)...

At 5 most kids have personal boundary issues and to be honest it is normal for kids to be immature to varying degrees...

What pisses me off is that your school allows people to exclude kids from parties. That is plain rude. My daughter's school has a rule, no invitations can be passed out in class unless ALL kids are invited. If you want to play "exclude" games...then the invitations must be issued outside of the school. As a result parties have dwindled in numbers and/or all the kids show up for the parties.