Sending Nudes

My boyfriend STILL tries to get me to send nude. I’ve tried and tried and physically can’t. I did once but it was just my boobs. But he wants the whole 9 yards where it’s every part of me and I’m posing and stuff. But things have happened in our relationship and I just don’t feel comfortable with nudes but he won’t stop pushing me for them. I don’t know what to think nor how to feel about this.