Have your teachers articulated their frustrations a little more in depth with you? With no training or understanding of Autism, the day can be very long. Perhaps asking what they need such as tools to help him (sensory ideas, busy items to slow his mind and keep his hands busy, etc.), adding in time that you can cover to give them a few minutes a couple times of day out of the room, etc.) It can be hard for a teacher; especially if what is going on in the room makes the child feel overloaded (sights, smells, sounds). Short staffing can be another hardship because often teachers feel like the child is giving a clear message, but they just don't have the one on one time the child needs. I am glad the evaluation process is underway. Try communicating with your teachers a little more and ask them what would help them in this situation.