I have some concerns

Okay, my son is 2 and he's talking ,but very little. My mom and my sister says that he may have autism because he's not talking like his cousin ( he's 3 1/2 years old).

My son used to say thank you and please, but now he doesn't say it and when I look at him and say please, he gets mad.

He can say his colors, yes, let's go and some other words. But not thank you or please.

I don't mind if he is or has a learning disability or anything. To me he's very smart. I'm going to schedule a doctors appointment next week ( his doc is out of town right now) has this happened to any one's child ? I looked up online what are the signs for autism. But he's not displaying those. He knows his name, he'll come to me, the light doesn't bother him unless he's trying to sleep. He looks at me in my eyes.

He shares and everything. Am I over reacting? I'm just one worried momma bear.