Tell him that it makes you feel insecure and that you don’t find it funny when he says inappropriate things like that. If he still thinks it’s a good idea to make reference to your vagina make reference to his penis being ugly, smelly, cheesy or limp in bed. No one’s body is perfect. Most people don’t have attractive genitals. Porn gives people the wrong idea.

Men are obsessed and intrigued by women's genitals. He probably meant nothing by his comments. Love your body and own your big clit! Knowing men, he probably actually loved it too but he expressed it badly and therefore inadvertently reinforced your thoughts about it. Talk to him.

I understand how this would get to your feelings.
At first you said you laughed it off and later started too make you feel insecure.
Its really important to remember that we are our own harshest critic and bodys come in all shapes and form. I have never met anyone that doesn't have at least one pet peve about their body.
If he says it again make some remark along the lines of.. lett me take you up the a$$ with it then. Or atleast mines bigger.