Translation:Not your father, not your girlfriend, nobody.
I think it depends on the question previously asked.
If the question uses the verb "sein" (eg: "ist das mein Vater oder meine Freundin?"), then this is correct, as that expects answers in nominative.
If the question uses another verb, this would probably not be correct, as it would normally expect an accusative/dative/genitive (eg: "magst du mein Vater oder meine Freudin?"
You just insisted that Freundin should be translated with Girlfriend, which I did not find totally correct because "Girlfriend" implies a sentimental relationship, or whatever you may call it, whereas "Freundin" is simply the feminin of Freund. However, I complied with your intrepretation by always translating Freundin the way you seemed to like, eg. "Girlfriend." So why exactly are you suddenly not accepting it anymore?