Impulsivity

I have a 5 year old girl. She is academically normal but is impulsive. I find that she is more impulsive to tasks that she does not want to do or that she finds difficult. She is in Kindergarten and socializes with kids fine. She is always smiling and everyone finds her so cute. She often ignores directions but she's not rude about it , she doesnt say "no" she just keeps doing whatever she wants to do. She likes to be the first in line and will cut other kids but not with a mean spirit (she doesnt push kids out of the way). She just steps in front of them.
I think she cant control her behavior. She would like to but often thinks she behaved when in fact she didnt. She is not "always on the go". She can sit down and do a task she likes. SHe doesnt have to be standing but she does have to be asked several times at school to do complete a task.
Im not sure if this is ADHD. Im not sure what to think but any insight will be helpful. She was born at 27 weeks. She does receive OT, PT and speech. She is classified Speech and Language and attends a general ed class. They have a general ed and spec ed teacher in the class. Like I said earlier academically there are no issues -they describe her as impulsive.  
thanks for your help.

[Sandman2]

Compared to other stories you read on this forum for 5 year olds, she sounds pretty good.  My first guess would be that she has good to very good intelligence and has learned how to take advantage of her situation.  She is only 5.  At that age, they are not known for self control.  It sounds like the school has a pretty good handle on her situation.  Talk to them,  they see a lot of kids, so they can compare and give you a feeling for where she is on the spectrum.  I would definitely make sure you are very consistent with her.