First of all, let me commend you for not giving yourselves away before marriage. I think each couple such as yourself should be commended for that. We deal with such negative influence in the media it just makes me sick. So, good job, and stay pure! (easier said than done, right?!)
I’m speaking strictly from experience, as my husband and I just got married this last July and we stayed pure until then. From everything we experienced up until we got married, I don’t want to sugar coat how the next year will go for you. It was one of the most difficult things I had to deal with, and the biggest thing for us was 1. we were, and still are, on the same page in our spiritual walk. You said “our differences in faith are less of an issue at the moment than what is directly on the doorstep right now: sex…”. To be honest with you, Anon, if you and your fiance are not on the same page spiritually and don’t have that squared away, figuring out how sex works in the catholic church will actually be the least of your worries. Right now it probably seems like the biggest struggle (it was huge for us too! I understand!), but until you get on the same page with your spiritual walk, things will be complicated and just get worse as time goes on. 2. we held each other accountable. If things were physically getting out of hand, even just kissing going too far, we stopped and backed away. The key for us was stopping the physical part before it got out of hand. And, I don’t mean to put any pressure on you, but you’re the one in the relationship who will have the most trouble with this. It was funny after my husband and I got married, he says , “wow I can think so much clearer!” So, be strong and make sure you both hold each other accountable.
One last piece of advice I have is to surround yourself with Godly people and a positive influence. They will be the best support (or should be..) that you can find for helping your situation.
Things will be hard (especially for you!) and probably get harder, especially the last few weeks before your wedding, but don’t give in to temptation! The enemy wants you to stumble on your human instinct! Don’t give him a chance!