YOU SAID:

I am really good at nothing

INTO JAPANESE

私は何もが本当に得意します。

BACK INTO ENGLISH

I was nothing but really good.

INTO JAPANESE

私は、本当に良いことがなかった。

BACK INTO ENGLISH

I really have not.

INTO JAPANESE

私は本当にないがあります。

BACK INTO ENGLISH

I really have not.