Is it normal that i'm not sure.

I've been with my boyfriend for almost 4 years now and we've never had sex (i'm a virgin but he's not. I'm 18 he's 19). Sometimes i think i'm ready to have sex with him and sometimes i think i'm not. He supports me and has never pressured me to do it.

I don't know if i'm 100% ready to do it so he tells me to wait. Is it just me or it's because i'm not ready to do it? I don't want to feel like i'm ready and do it and then regret it.