OP, first of all, thanks for those pictures.
Second, it makes me worried when I hear people say they are in a quest to improve themselves. To me, it sounds as if you were a bad person as of now that needed to be improved. Which then I saw it appear right after that when you say you think you are a boring person because you have nothing interesting or funny to say. But really, why is it so important to be interesting to someone else? Why is that an issue to be fixed, you know? For whom is that issue going to be fixed, for you or for others? And I don't know where you live or how your life is, but perhaps they are just not the people you'd like to hang out with. Not because they ought to improve themselves, but that doesn't mean you are the one with an issue either. Sometimes people have different interests or, which is more incredible, what makes a good conversation is something in the way people respond that somehow makes it easier for us to couple with this or that person and not so much with another. It does not depend solely on us or solely on others, otherwise it wouldn't be a conversation.
You didn't come here for this advice, but I'm giving it anyway. Consider, before going further with this book request, the things you find interesting, the things you find funny, whether it is in entertainment, sports, science, in school, in work, in spaces to go, in things you did not do before, in people you meet, and so on. Not what the other people might find interesting in you, but what interests you, what is that in which you are willing to invest yourself to be doing.
You say you don't want theatrics, but I was thinking you would perhaps like to join a stage acting group. That could help you not fix the issue you think needs fixing, but put things in perspective between you and others and how you relate to this image you have of yourself. They are usually lovely and welcoming people.
It's funny to ask on how to "have things to say", when a good part of "things" is in doing them other than talking about them later. That comes as a bonus.
There are books for all kinds of speaking and really some for the types you want. But I won't recommend any of them, because they'll answer your question and I think your question is wrong and having it answered won't make you feel better, and you'll feel even more in need of improvement.
Everything is ok as it is. But what do you want to do?