YOU SAID:
I was using was in the past until I wasn't
INTO JAPANESE
私が使っていたのは過去でした
BACK INTO ENGLISH
I was using it in the past
INTO JAPANESE
過去に使っていた
BACK INTO ENGLISH
I used it in the past
INTO JAPANESE
過去に使用しました
BACK INTO ENGLISH
Used in the past
INTO JAPANESE
過去に使用した
BACK INTO ENGLISH
Used in the past
Come on, you can do better than that.