I am not confident while speaking...even to my own parents. How can I improve?

Its not that I don't have a sense of humour or that I dont speak much. But when I speak, I feel like I cannot express correctly what I mean and I fail to explain my cause to people and even to my own parents. Hence sometimes I feel like they dont take me seriously. And they not taking me seriously angers me more and makes me behave rudely to them which I dont want. Its something like I cannot put the correct words or frame my sentence in the correct way or maybe say it in the correct manner. I always have a feeling I mess up with my words. And also when some of my friends or my relatives say something to me joking me or say being sarcastic, I fail to come up with a good reply and feel dejected. Sometimes I end up saying something which I later realize, I shouldnt have said it, I have attention-seeking tendencies and often make up stories to grab attention. Sometimes while I am among people, I have a feeling I go unattented and feel odd. I have OCD. Dont know if all of this has to do something with that. Please help me. I hate this.