She's Living Too Far in the Future
Marriage clearly shows your intention to spend the rest of your life with your girl, but not necessarily a desire to jump immediately into a massive brood of kids and other mom and dad stuff.
You may notice that since your proposal a lot of her time has been spent planning for the future. We're not just talking wedding plans here, we mean far, far into the future: how many children to have, choosing their nannies and schools, and lavish decorations for a house you don't even own yet. These are warning signs that she could be playing catch-up with her already settled friends.
Marriage should be enjoyed in and of itself. It would be nice to have a few years as a happily married couple without all the other things that get in the way. Kids and an expensive house are good in time, but just enjoying the marriage is great. Any reluctance on her part to slow down should be treated with caution.
OK, so we've noted that the finer details of the wedding ceremony probably aren't your major interest or even your remotest concern, but you would like some input into how the day goes. If there's one negative trait that's bound to surface in your oh-so-perfect fiancée, it's going to be her over-controlling side.
Even though she's undoubtedly had this planned for years, there should be some room for your suggestions. She may hate the idea of your entire college football team attending, however, if it's what you really want then there should be some compromise.
Her obsessive, over-controlling side doesn't paint a very pretty picture of future domestic bliss. Instead, images of a hen-pecked, beaten-down husband spring to mind. Things to really watch out for include a no-drinking rule, limiting the number of your buddies and insisting that she choose your clothes on a daily basis.