(I'm back - have been with clients all day).
Christina F, the plum dress runs more TTS.
Suz, you might like to try the polka dot in a US2 and US4, since your shoulders are broader than mine. Try a US0 and US2 in the purple.
Lisa p, Topshop sizing is very inconsistent, but perhaps try the polka dot. Size up one size. That's what I did.
mthsofthemoon, you are lovely. We are staying in Positano and Sorrento.