There are more native English speakers in my country than yours
That’s for sure! My country’s native language is not English, so you’re again right that my landlocked country is not an English-speaking one.
Continue using whatever you want, don’t be surprised if your illogical words don’t make sense to someone else.
If you want to go by sheer numbers, I think in India there’s more native English speakers than in US and they use a variation of British English and as far as I know, seafood there means what any sane person would assume. Hell, you don’t have to go with English, my language’s version (literally translated to English as “fruits of the sea”) also means only fish/shellfish from the sea. And I guess most (if not all) countries use it the same way.