Nice to hear from you, and thank you for answering my snoopy question about age, but if I know the age range is 19-20 that does help fine-tune the reply some.
He sounds like a real treasure and it's great that you have each other and I'm glad and personally I don't think your expressing yourselves together is a sin at all; I only suggested Ms. Elliot's books because that seemed to be the option that interested you, and that's fine.
It seems every time a person posts, there is one sentence that jumps out at me. This time it was "I'm not sure how to start discussing with him..."
Go ahead and point & laugh if I am wrong here, but that lil phrase just may be the essence of the situation right there.
There are plenty of subjects that are hard for women to bring up, especially if they are kind loving women who want their men to feel comfortable and happy. It sounds like you were both able to talk about marriage, but the harder nuts and bolts of life are just... harder, and not only for you. For example, here is one useful phrase which is difficult for many people to use and to hear. "Sex? What a wonderful idea! Let me pick up the phone now and call so we can go get an HIV test together first. Wouldn't that be romantic?" I've used that one, and it is interesting to watch how the most self-confident conquistador can be thunderstruck at the prospect of getting tested.
If the issue of sex came up before and has never come up again, then I would wonder why. Did he just forget to ask ever again? Or, is he busily forging his own answer with you and without words?
Even after marriage it can be VERY hard for couples to talk about some things or ask personal questions: How much money do you keep in that retirement account? Have you booked your colonoscopy that the doctor ordered?
So what a great time to practice!
Reading your posts, I am still gathering a picture of exactly what you need, for yourself, to feel thriving and fluorishing and comfy as a woman and as a Christian at the same time. Seems like your guy's behavior is healthy and happy for him. But at 19 you get to work out a LOT (a lot) of path-finding for yourself and figure out who you are, not only with regard to courtship but to career and education and where you want to live and all.
So, sounds like you two get to do some TALKIN.' You can rehearse on us if you want.