Hi lulu and welcome to Cruise Chat.
What a lovely dilemma to have! There are services that will pick up your luggage and deliver it to the ship at your embarkation port. Sometimes they want to pick it up as much as 3 weeks prior to sailing, but it may be worth it to you. I don't have the names of companies off the top of my head, but perhaps someone else can help you.
As for as how to pack, I suspect most people pack for a 10-14 day trip, and then start at the beginning with a little help from the ship's laundry.