when to have sex?

hi! i’m 18 and i’ve been with my boyfriend for almost 2 years. we have never had sex. he had sex with his ex but i’ve never done anything before.. he’s tried a few times i just always stop him. we have a great relationship i just don’t feel like it’s ever been the right time for me. i don’t necessarily have anything against sex before marriage but i grew up in a very strict household where that was like the worst thing you could do. do i have some sort of underlying trama there ? idk. how do i know the right time to try ?