Carter, the less you overthink this, the easier it will be. Have you checked out Une Femme's Paris packing posts? i've done ten days to Europe in a carryon no problem. You just have to have clean underwear and tees. If you care about wearing repeats, don't go this route.
Europe is getting so casual. You won't be out of step in slim jeans and Nike or Puma running shoes. They all wear them, with scarves, jewelry, jackets or trenches. Even to lunch, even to the theatre. It's just the most practical thing. Just be sure they are not in shocking white leather! Loafers with a good sole would be great too. You don't want little thin soled flats in case it rains or in case you will be using the metro systems much, where it can get pretty dirty down there. What I've done for fancy dinners is put my heels in a tote to discreetly change into from flats. That will save you a lot of misery if you walk to dinner, which is really fun.
Go neutral. When I go to Paris especially, or Italy, I forget how neutral they are. London is a bit more colorful. By spring you could break out the light neutrals, but I've never seen white pants much outside of summer. I am sure you could go all black and still be in step. Plus you will always look good in your pictures in the neutrals, and you'll never think," Oh gosh what was I wearing?"
For spring in Paris last time I built a capsule around taupe, lavendar, white and light citron. Everything swapped out so well that I would pack that same wardrobe in a second.
I bring stuff to Europe that I am ready to leave behind. That way there's more room to bring home things and gifts. For instance, bring and old bag and buy a new one at Lancel!
If you tell me where you are staying in paris I can see if I can tell you where to shop and eat. I have some faves, mostly in and around the 1st arrondisment. I once lived in London and things change, but I know if you love Indian food you are in for a treat.
I have ideas for tea, and for perfume sniffing, if you are into that.
Have fun planning this wonderful trip!