He doesn't have to have a diagnosis of autism to receive therapy if his social communication and communication skills are that far behind what they should be. If you are in the U.S. you can demand that the school system do a free evaluation to assess his skills. If he's repeating things people say, that is commonly called "echolalia". Kids with verbal apraxia may do that sort of thing as well. There are also language processing disorders. My sister had that as a child and went through speech/language therapy and got pulled out of class for an hour every single day until she was about in 4th/5th grade. She does not have autism, but she had some serious language processing issues! She's 8 years younger than I am, so I remember pretty well what she went through. I also remember my mom had to stay on top of the school system. My mom was a teacher before she had children, so she knew a little about the school system. There are laws intact now that help the parents. Well, if you are in the U.S. Can't vouch for other countries. Find out what your rights are. You can google things (again, if you are in the U.S.)... things like IEP. You could ask your child's pediatrician. They should know how to advice you on things or at least point you in the right direction! And give you someone to contact!
Firstly what country are you in?
What professionals have assessed and observed your son?
Have any professionals seen him who have experience of diagnosing autistic spectrum disorders?
Who says he isn't autistic, is it his school teacher?
Has he been assessed by a Speech and Language Therapist.
I really don't think their explanation for his poor communication skills and repeating what you say is down to being 'spoilt' by you.
Google 'echolalia and autism' or 'delayed echolalia and autism' and see if that is what your son is doing. If it is it means he has a speech disorder which is closely associated with being on the autistic spectrum. I would then go to your child's paediatrician or your local GP and tell them about your son's difficulties and tell them that you want your son to be referred for assessments by professionals who have experience in diagnosing autistic spectrum disorders.
If he is on the spectrum it is good that he is talking, but he will need Speech Therapy and he will need his school work presented in an autism friendly way. An Educational Psychologist should be already involved with him if he is in a Special Education Program, if not you need to ask them to get one involved with your son.
Even when his speech has developed (with help from the therapist), if your son is on the spectrum, he probably won't talk about what he did at school etc. This is the social use of language and those on the spectrum tend to use language only to get what they want/need or to talk to people about the things they are interested in. But you can ask him specific questions like 'did anything good happen at school today', or 'did anything made you sad at school today' etc. This makes the question specific instead of a general open ended question like 'what happened at school', or 'what did you do at school'. Those questions are too difficult for them and they cannot answer in the way that we do and give the information that we do because they don't work in that way and don't notice the things we do or give importance to the things that we do.