I'm a medical student and a woman who sometimes has sex with men. You are hilariously misinformed. The problem with larger penises is the cervix, because when you hit the cervix most women experience pain. There is also the problem of needed to prepare the woman for larger insertions that many well-endowed men ignore - if she isn't properly lubricated, it again can be painful. And there are anatomical limitations for some women, depending on if your uterus is retroverted or anteverted which can make it easier for a man to accidentally hit the cervix.

In conclusion, your ideas are bad, and you should feel bad.