HD, I think you are on to something here! The convo sounded great and you articulated your feelings in a clear but concise way. Continue to stand your ground because no doubt she will retort with, "Well then you are right--we will not be married in ten years if that is your requirement." Then you will have another opportunity to remind her that this is HER choice to make and that you are only telling her your true feelings.
One suggestion I was going to make was to NOT have this discussion on vacation--why ruin the good feelings you have going on? Everyone looks forward to vacation and a big, heavy discussion on the trip there would dampen that, imo. Why not have it this weekend and have some sort of resolution or answer in place by the time you leave? I understand that the drive will give you lots of time in which to discuss it but it sounded like a short conversation to me and I doubt she will want to go in depth about it, anyway, at least not right away.
We are all pulling for you; this sounds so promising!