I'm one of those! The accepted term is Little Person, or just LP. Dwarf is fine too (it's also the name of the medical condition, not just a fantasy race). Honestly most anything is fine except midget -- that's straight out because it was a carnie freak term.
I am an American and I don't even know which term to use. Honestly, people are offended way too easy at this point, and that's coming from a millennial.