Translation:You have never spoken with my sister.
Alex. I am not sure if you noticed, but you have changed the sentence. The 'at all' at the end of the sentence 'makes no difference (at all)'. Writing 'makes no difference (never)' changes the whole meaning. One is an assertion, the other is a reassertion. You have never spoken to my sister (at all) is an addition to the translation, a reassertion of the statement. That is the difference between never and at all.
Forever and never are opposites. Ever and 'not ever' is a negation. You could visualise never as 'direct', and 'not ever' as 'indirect'. Never is the usual word. But to prevent repetition in a conversation, you could reply not ever. I am not sure what the equivalent is in Turkish:(
If you leave out ‘hiç’, then the sentence reads ‘you have not spoken to my sister’. That implies that the second person should speak to the sister to resolve a query of some kind. The ‘hiç’ changes the sentence to an accusation, where only the dialogue can determine the meaning. The sentence is okay. We just don’t know the dialogue.