YOU SAID:

I really think that you should go to the bathroom.

INTO JAPANESE

本当にトイレに行くべきだと思います。

BACK INTO ENGLISH

I think you really should go to the bathroom.

INTO JAPANESE

本当にトイレに行かなければならないと思います。

BACK INTO ENGLISH

I think I really have to go to the bathroom.

INTO JAPANESE

私は本当にトイレに行かなければならないと思います。

BACK INTO ENGLISH

I think I really have to go to the bathroom.