The word קצין means officer in the sense used in the armed forces: someone in a rank of authority. "Police officer" is not a good translation for קצין משטרה because "police officer" can refer to any policeman/woman.
This doesn't translate well. In English every policeman is an "officer" while in Hebrew a "קצין" it is only someone of a high rank. When I've called a member of the police a "קצין משטרה" they have corrected me and said there were only a שוטר. This translation is wrong. The issue of policeman/woman just confuses the point.
so a better translation - if you were to say this - is I am an officer in the police force, or something like this with ב?