YOU SAID:

i was going to the store when my cat was walking backwards yesterday

INTO JAPANESE

昨日店に行こうとしていたとき、うちの猫が後ろ向きに歩いていました

BACK INTO ENGLISH

My cat was walking backwards when I was going to the store yesterday.

INTO JAPANESE

昨日店に行ったとき、うちの猫が後ろ向きに歩いていました。

BACK INTO ENGLISH

When I went to the store yesterday, my cat was walking backwards.

INTO JAPANESE

昨日お店に行ったとき、うちの猫が後ろ向きに歩いていました。

BACK INTO ENGLISH

When I went to the store yesterday, my cat was walking backwards.