Which sounds more correct?

[dilodi83]

Are they all grammatically possible?

- Since December 2004 on, when I came back to England, I have been working for Armani Brand.

. From December 2004 on, when I came back to England, I have been employed at Armani Brand.

. From/Since December 2004 on, when I came back to England, I have been being employed at Armani Brand.

[SoothingDave]

Since December 2004, when I came back to England, I have been working for Armani Brand.

or

Since December 2004, when I came back to England, I have been employed by Armani Brand.

"From December 2004 on" doesn't sound good to me.

"I have been being employed" is not grammatical.

[5jj]

"I have been being employed" is not grammatical.

This form is grammatical, but it is rarely needed or used. It is not appropriate in dilodi's sentences.