Gavinmad
Mr. Poopybutthole
The only time she legitimately looks a bit ill is her being pale and depressed in Rivendell. The other scenes with her being sick are Aragorn dreaming and Sauron trying to deceive Aragorn with the Palantir in the extended cut.I haven't watched RoTK in a few years, and with it laid out as you did it sounds plausible, but aren't you forgetting that it also tied into Arwen collapsing into some sort of mystery sickness, and then boom, ring destroyed, all better? It just seemed invented for no good reason, as if those long, heavy movies needed even more high stakes tossed into the mix.
If the idea was for her to be wasting away because of the power of the One Ring, I don't think the original plan to have her bring Anduril to Helm's Deep and join the fighting would have made it as far as it did.