Welcome to the forum!
Here are my thoughts:
Day 1: Do you already have the ET and Madame Brasserie booked? If not, I'd move them to another day. ARe you flying from the US? Many experieice travel tiredness and you might not be able to enjoy a really special restaurant meal this evening. Since you've got a LOT of time, I'd defer this by a day.
Day 2: This looks good but light. I'd probably add the Conciergerie to Sainte-Chapelle as it is right next door. What day of the week is this? you might want to walk over to the flower or bird market by the Cite Metro stop then head to Notre Dame to see it with the scaffold coming down. You can pick up a sandwich at Hure which is right down the street from Notre Dame and eat somewhere facing the Seine or in the park across the river. Any interest in the Crypte Archeologique or the Deportation Memorial? Those are at either end of Notre Dame. Are you attending a performance at Opera Garnier or doing a visit. Boat trip on the Seine?
Day 3: Jardin du Palais Royale will take about 15 minutes. It is quite small and not really as much of a garden as you might think. Are you interested in gardens? If so Jardin des Plantes is excellent as is Luxembourg Gardens. Vivienne Gallery is also fairly small. If you are a shopper you might be able to spend an afternoon here. There are other covered arcades in the area as well. I would have this site in your back pocket for a rainy day. It can be slotted in any time but if the day is lovely, you might consider an outside venue. You could easily move ET and Madame Brasserie today and juggle the other sights around your timing for those things.
Day 4: Looks good. All day in the Louvre is over my max but you might be younger and stronger than I, hahah! DO stop and take breaks at the various food outlets inside the Louvre. A cafe and Croissant about 10, lunch later. I can usually last for 3 hours and then the crowds get to me. If it's nice I head out to the Tuileries, grab a sandwich and drink from the Eric Kayser kiosk right next to the Carroussel Arch and pull up one of the green chairs and people watch. OR I eat lunch in one of the restaurants on their umbrella covered terrasse.
Day 5/6: Are you interested in any other museums? Musee d'Orsay? Orangerie? Cluny (Museum of the Middle Ages)?, Marmottan ( Monet)?
Day 7: I'd plan to spend a full day at Versailles but to me it would not need 2 days
Day 8: Check out Paris Walks (www.paris-walks.com ) to see if any of the walks they offer appeal to you for today or any day.
Day 9: Day trip? Are you interested in Gothic Cathedrals like Chartres? Gardens like Giverny? Champagne tasting at Reims?
Day 10: I'd do museums in Paris today if that is of interest to you. Resistance and Liberation Museum? Army Museum? Catacombs?
Day 11: I'd do another day trip from the ideas mentioned above
Day 12: Finish up any museums and gardens that might be of interest. Maybe a final Paris Walk or a food tour? There is a Julia Child food tour I've got my eye on for next time.
What a terrific amount of time you have!!
It will help others to know what your interests are. What I love about Paris might not be what interests you!