Because your description includes developmental and speech delays your son may be having bhavioral difficulties because of the reasons for the delays. Having therapy to resolve his delays will improve his behavior. Your son's behavior sounds much like that of my grandson who is now 4.
Professional help is available without cost because of a Federal law mandating that all states provide evaluation and treatment of children who have a disability that will affect their success in school.
In Oregon this is provided thru the Educational Service District. You can call the local school district to find out where you would apply for evaluation.
My grandson was evaluated when he was nearly 3 and is having therapy. He started with speech therapy during the summer and then went into Headstart, even tho he wasn't qualified based on parents' income, because he could continue with speech therapy. He was difficult to control within the classroom. He refused to co-operate, threw temper tantrums and began hitting the teacher. At a meeting attended by everyone involved in his treatment, his parents agreed that he should be placed in a therapeutic preschool where he is now. Again the parent pays nothing. This is a service of the school district.
Along with therapy for my grandson the school district provides support for his parents. My grandson is doing much better with both speech and behavior.
I urge you to make an appointment for evaluation right away. Early Intervention for ages 1-5 is the name of the program. The earlier the intervention the better it is for both the child and the parent. We wish that we'd known about the program so that he and his mother could've received help earlier.
I've answered several mother's questions including web site addresses but I don't remember them now. I remember other mothers writing about this program. Perhaps other mothers can add to my information.