Poppin’ the cherry 🤭

So I’m 21 and I’ve never had sex, but I’ve been with this guy for a while and I feel so much peace around having sex with him. We’ve talked about it and he understand how big of a deal this is for me. Anyways, what should I expect?? Or like tips for preparing for this? I feel like such a child 🤷🏻‍♀️. Also, we have amazing physical chemistry and have done basically everything else before so I don’t want to go into this expecting the most amazing experience because, realistically, it probably will be super painful and not like some romance movie right??