YOU SAID:

yesterday I went to the shops with my mum she was very slow

INTO JAPANESE

昨日、母と一緒にお店に行きましたが、母はとても遅かったです

BACK INTO ENGLISH

I went to the store with my mother yesterday, but she was very late.

INTO JAPANESE

私は昨日母と一緒に店に行きましたが、彼女はとても遅刻しました。

BACK INTO ENGLISH

I went to the store with my mother yesterday, but she was very late.