Condom nightmare

Omg girls, okay so I've been seeing this guy and we're pretty much dating, we've had sex, but when it comes to putting the condom on... He doesn't do it right!! I've offered to put it on but I haven't told him he's doing it wrong, he doesn't give his poor penis any room to cum and I'm worried that it will overflow or bust!!! Help me!!! Comment any of yalls worries also