Body insecurity

I am 16 and a virgin but I have a long term boyfriend and we’ve talked about it and we have gotten close but I always stop it because I am insecure. My main insecurity that stops me is that I have big nipples and one is a little bigger than the other. I’ve seen bigger but they definitely are not small. And I hear guys at school make fun of girls with big nipples and call them gross. Any advice? I really would like to go further with my boyfriend and be comfortable