Possible Asperger's?

When my son started preschool at age 3, we began to hear about major behavior problems.  He would be aggressive with other children and could not stay quiet during nap time.  He eventually got kicked out of the first preschool for choking.  His teacher says she didn't think he meant to hurt anyone, but he could no longer attend.  We attributed it to our divorce and discussed taking him to a counselor.  He was with me during the summer (I am a teacher) and started a new preschool in August.  He has been having problems on and off all year.  He makes strange noises, gets upset over little things (ex: a small tear on paper, gets out of line while coloring), and has been aggressive towards his classmates.  I have also noted he has been biting himself.  His teacher said she would never describe him as "mean" even with the aggressive behaviors.  It is more as if he can't help himself.  He has a lot of trouble at lunch when they have to sit in very close quarters.  He has good days and bad days.  At home, we have a few issues like talking back/"lecturing" but for the most part he is happy and well-behaved.  We have been taking him to a counselor and she mentioned she was picking up an "aspergers vibe".  After my discussion with her, I decided to have him tested for Aspergers.  He is very intelligent with a huge vocabulary.  He began talking at around 7 months and talks a lot.  He has a great memory.  He is obsessed with vehicles.  When he was younger, he lined everything up in a row.  He still does this, but not all the time.  He does get very upset if someone moves something out of place.  His eye contact is so-so.  Sometimes he is very alert to others, but I notice most of the time it takes a little to get his attention, and I constantly have to tell him someone is talking to him and he needs to respond.  I also think he has sensory issues.  I have an appointment for him soon, but he is having so much trouble at school that I wanted to get an expert opinion now.