I hope you don't mind me saying this, but do you watch streams by other VTubers? I think you could really learn from them! They put a lot of effort into crafting their voices—laughing, using varied intonation, and so on. Right now, it sounds like you're just reciting the words...
I do watch a lot of other Vtubers, and I think that they do amazing jobs. But with me that's honestly just the way that I speak, I have a very monotone and flat voice.
