YOU SAID:

You don't remember how long it has been since you've taken a shower.

INTO JAPANESE

シャワーを浴びてからどれくらい時間が経ったのか覚えていません。

BACK INTO ENGLISH

I don't remember how long it's been since I took a shower.

INTO JAPANESE

シャワーを浴びてからどれくらい経ったか覚えていない。

BACK INTO ENGLISH

I don't remember how long it's been since I took a shower.