If you were a British overseas territories citizen only because of your connection with Hong Kong you lost that citizenship on 30 June 1997 when sovereignty returned to China.
However, you became a British overseas citizen if either:
you had no other nationality and would have become stateless
you were born on or after 1 July 1997 and would have been born stateless
if one of your parents was a British national (overseas) or British overseas citizen when you were born