Behaviour issue in 2. 5 year old son.

My son is 2.5 years old. And he is 92 cm long 12.5 kg weight. He has speech delay and much obstinate. He becomes aggressive without any reason. Even he is doing any work alone. He suddenly throw things and after that that hitting both hands on hand even after he hits his head on bed or even floor hard and felt injury and cry. Even his catching power is good . He understand alphabets very well even you changes order whatever even if something is written on clothes he catches it and read. And he knows counting from 1 to 10 . And also knows animals name. But he doesn't say himself. If someone asks then he will answer otherwise he doesn't even say papa mummy. But when ask who is he then he say mummy chacha papa mama bua . And also clearity speech is not there. He knows according to his age but can't express through words. In a sentence he speaks, we can understand only last word which is important to understand. Other words no one can understand. Like uhanhuhm cow. Jivkykhg doggy .