Tiffany actually has all the sizes on their website, which is why I have been looking at it so hard because I know I can get it quickly. It is my own fault for waiting so long that I'm in this position with limited choices.
Anyway, I did it! I decided a little tradition in my life can't be a bad thing and as much as I loved the DY crossed bands I just couldn't see it being a "forever" piece. I ordered the Metro in WG and the Novo band (1/2 not full eternity) in Platinum to see which one I like better, but I will probably be going with the Metro.
I went by a local store and got sized before ordering and ended up deciding that a 5.5 will probably work better. The 5 fit better in the finger but it was tough getting on and off (read: painful) and since I'm at my lowest weight of my adult life it seems more likely than not that at some point in the life of this ring I'll gain some weight.
They were able to expedite the shipping for me so they will both be here Thursday which gives me plenty of time to decide before the big day next week.
Thanks everyone for all of the help and ideas!
