Norm's reply is really great.
Even so, you are going to pack way too much. I suggest you not shop for any more clothes, and after you pack remove half of them.
Nobody, repeat, nobody cares one little bit if you wear the same thing two nights or three or four, as long as you roughly adhere to the dress code on which Norm has elaborated. At the risk of being ridiculously repetitious, nobody cares.
Although we always adhere to the dress policies (well I cheated two weeks ago on the Millie transatlantic when I wore a tie and sweater instead of a tie and jacket one night), we do not overpack and we mix and match to make things work. You will SUFFER if you overpack.
Unfortunately, despite your best efforts to adhere to the dress standards, you will still find those who flaunt them openly, and you will find that Celebrity does nothing to enforce them.
On the same trip one guy came into the deck 10 cafeteria with no shirt and sat at a table next to us. We complained to a waiter who passed it on to his boss. About 10 minutes later a supervisor of some sort came in and told the guy to leave. I was surprised, and it was evident that the staff didn't like having to do this.
Anyway, for a 14-day transatlantic, with an additional 4 days in Barcelona and 4 more days in Madrid, we did fine with two normal suitcases, a garment bag and two small hand bags (NOT the small roller suitcases that people call hand luggage these days). We didn't do any shopping beforehand and, as usual, packed the afternoon before we left.
Please don't make it a bigger deal than it is. You'll be much happier in the long run. Honest.