Is it normal for my boyfriend to have such a big penis?

My boyfriends penis is 10in long &the width of my hand. I don't have a small hand either. Every time I go down on him I almost choke. I have a big mouth, bigger than most peoples. And I still almost choke on it cause it's so big and is hard not to accidentally use my teeth. It hurts a lot to have sex but ends up feeling good a while into it, we've been having sex for 2 months now. is it normal for it to hurt still to have sex? is it normal for him to have such a big dick?