Tears in my eyes after reading this. I've been in a similar situation before. After a lot of thought during that relationship with a non-Mormon, I laid out exactly what struggles I was probably going to face: I was worried about my own faith. Every new set will see your man with fresh and hungry eyes as a potential golden contact. Catholics basically married catholics and protestants basically married protestants. Having said this, there are several aspects of this particular religion that you need to be aware of as these will greatly affect how she will approach you and the relationship as a whole.
Sorry you had to go through this, but it's for the best if she's about to leave on a mission. This helps us out a lot, we dont feel like we are missing parts of each others day and I dont keep him up all night talking. He realized his dream of being a specialty surgeon and having a family but leaves the dirty work to me. I have dated all walks of TBM women TBM women are closet freaks.
I wish I know things better and would have taken a different path in life. It's not that she doesn't believe you right now, but it is a bone she will never drop. Trust yourself, trust God and enjoy the beautiful relationship that you have.
I can say this. I realize that the answers to many of these questions may be different for every family, and that we need to continue to discuss them more as a couple as we continue to think about our future. Get her to explain what she believes, and how it might differ from her church.