SOOOOO I need some advice.

I'm with this guy and I am having a lot of trouble trying to initiate any sort of sexual activity. I have such a lack of confidence in my looks and my abilities and so me trying to start any thing is a struggle. I'm scared that he's going to be disappointed or something when we do do stuff. He has done things to me & he says it's fine that i haven't done anything to him, but i don't know, I'm stressed ! I don't know why I feel like this with him, I guess because I like him a lot and don't wanna mess things up, but how can I gain some confidence and take initiative?!