kissing

I'm in high school and this guy and I have been liking each other for the past 3 months. He knows I'm super shy and I'm nervous about my first kiss. And this is a guy who's had experience. Anyways he's "attempted" to kiss me twice and it didn't really work out cause I was so shy and walked away. The 3rd time he leaned in but I just got super super nervous again, couldn't do it and walked out the door. He knows I'm really nervous and he's been waiting and we've talked about it but I really don't know if I'll ever kiss him because of how nervous and shy I get. Any help ?