I live in an apartment in Hong Kong and believe I am in a similar situation
as yours. My radio is a cheap, made-in-China Kaide.

I don't have an active antenna. Instead I simply put a 6 yard insulated
wire (clipped to the radio's telescopic antenna) outside the room window
and have it run horizontally to the balcony. Reception improves a lot.
Certainly better than using the telescopic antenna alone. I am getting
good SW reception from as far as Radio Australia. Broadcasts from
transmitters in Singapore (BBC) and Guam (VOA) are clearly heard, too.

What I couldn't get is the broadcast from the (1) smaller transmitters of
Radio New Zealand and Radio Singapore, etc, and (2) transmitters in
Europe. However, the bands are so flooded with the Chinese (domestic?) SW
broadcasts that I suppose these stations will simply be drowned out even
with a good outdoor antenna.