What Causes Slurring Of Speech In A Extrovert 2 Year Child?

hi this question is regarding my two and a half year old son,he has just started going to preschool,i am really concerned about him as the teachers have advised us to visist a psycologist,as a child he is extremely bright,very found of learning new things,very fond of people s company,basically an extrovert,cheerfull child ,he wants to do things by himself very fond of electronics ,but there has been a bit of speech delay,he has starting forming sentences but still cannot express himself what he actually wants,since last week he shas started saying things such as im hungry ,give me milk etc,also he is very aggreessive at times,intially he hit his teacher and quiet a few of his classmates but now he does not use force at school,what his teachers are saying is his speech is not similar to other children and another thing he does not take change in activity easily,before going to next activity teacher has to politely explain him 2-3 min in advance ,at home also if he is into something he wo nt listen to us untill he is done with his activity.if he throws tantrum it becomes very difficult to handle him,he is full of energy,at times we cannot match his energy but one think i have noticed he does not like being told no but if we make up a story ,he will believe us immediately and obey us.although he is very aggressive and hits children alot but many atimes it is untentional ,just because he cannot express himslf he uses force,and he is more innocent than his age grop children,he will never complain if other child has hit him or hit him first,many a times some children will just start crying when he is near them and he will get blamed he will never defend himself.he is more brave than other children and also exremely sensitive but does show his emotions easily remains cheerful,is he suffering from some kind of disorder