YOU SAID:

I'm gonna use the bathroom, but first I need to use the bathroom

INTO JAPANESE

私はトイレを使うつもりですが、まずトイレを使う必要があります

BACK INTO ENGLISH

I'm going to use the toilet, but I need to use the toilet first

INTO JAPANESE

トイレに行きますが先にトイレを使わないといけません

BACK INTO ENGLISH

I'm going to the toilet, but I have to use the toilet first

INTO JAPANESE

トイレに行きますが、先にトイレを使わないといけません

BACK INTO ENGLISH

I'm going to the toilet, but I have to use the toilet first