I would go ahead with your plan to purchase Rick's Switzerland and Pocket Florence books. That leaves these destinations:
- Mont Saint-Michel.
Frankly, I would have started with the big France and Italy books and cut them up. But in case you don't want to do that now,
Rick has a few "Snapshot" books that you may not be aware of, including for Normandy and for Milan and the Lakes, available in both Kindle and paperback editions. These are actually just chapters drawn straight from the bigger France and Italy books. Note publication dates. They still cover more than just your listed destinations. For instance, the Mont St-Michel section could be photocopied on just 9 sheets of paper (or 4-5 double sided) if you find a copy at the library, and just a few more pages for the mid-Lake Como info. I don't see a snapshot for Strasbourg and Colmar and that chapter is longer to photocopy. Also no Snapshot for Brussels and Bruges, but we have a book for Belgium.
I do recommend Rick's Florence Pocket over the Lonely Planet, especially if you like the books you have already. For the other areas, rather than the Snapshot format that Rick's publisher uses, Lonely Planet has the option of buying PDF versions of single chapters from any of their guidebooks (print at home and/or store on a tablet); see http://shop.lonelyplanet.com/europe/ and drill down to the chapter you need.