Informal:
* Ma fille: This literally translates to "my daughter," but can be used affectionately for your girlfriend or a close female friend.
* Ma meuf: This is a very casual and slang term for "my girlfriend." It's not appropriate for formal situations.
* Ma copine: This is a more formal way of saying "my girlfriend."
Formal:
* Ma petite amie: This is the most formal and direct way to say "my girlfriend."
* Mon amour: This means "my love" and can be used for a romantic partner.
The best way to translate "my girl" depends on the specific context and the relationship you have with the person.