YOU SAID:

You can't do better than that.

INTO JAPANESE

それ以上のことはできない。

BACK INTO ENGLISH

I can't do any more than that.

INTO JAPANESE

それ以上は何もできません。

BACK INTO ENGLISH

There is nothing more I can do.

INTO JAPANESE

私にできることはもう何もありません。

BACK INTO ENGLISH

There is nothing more I can do.