You would be nuts if you didn't try it on - think about it. The dress has been changed since you last wore it....You need to know that she made the changes and that it fits right!
Its not neurotic - its good business sense. : )
You should also get pre-approved for a mortgage because the housing situation is so crazy on Long Island, it's on the market for an hour and already has 5 bids on it...no joke. You must remember, you and your fiancee are now one entity and no matter how you busted your butt to have a good credit rating, his/hers counts just as much and if it's not very good, you need time to work those things out. We're learning this first-hand.