How to deal with how I feel?

I’m 18 and a half and have a boyfriend who’s 21. Although he’s my 1st boyfriend, I adore him and couldn’t ask for our r/ship to be any other way, and it’s as if I’ve known him for ages.

He’s a dream to me-stayed by my bedside in hospital when I had major surgery a few months ago, waited for me to finish high school for me to see him properly, just an amazing guy. I also like the fact that he’s not over-the-top with his emotions, in that he won’t tell me he loves me every single time we see eachother- I like it that way. Very genuine guy. Has jokingly mentioned marriage, kids and a future with me, which I have in most cases laughed off. Last night was the last time he did that.

Well, the thing I’d like to get down to is: although I feel strongly about saving myself for marriage, when we’re intimate, it can come to the point where I can see myself giving me to him. I have such absolute trust in him and I’d be his first as well. It’s just I don’t agree with birth control, (Catholic belief) which is all the more reason for me to save myself til marriage.

It can just get difficult to deal with these mixed feelings, cause although he isn’t that fussed for me to wait til marriage, I want to show him how much I love and trust him. But of course, I definitely acknowledge that there are the down-sides of this IF anything went wrong with us.

I know these are normal emotions, but how can I deal with them? Also, why would je jokingly mention a future, marriage and kids with me?

Thanks to anyone who responds.