YOU SAID:

I went to the store and bought eggs but forgot to get milk.

INTO JAPANESE

店に行って卵を買ったが、牛乳を買うのを忘れた。

BACK INTO ENGLISH

I went to the store to buy eggs, but I forgot to buy milk.

INTO JAPANESE

店に卵を買いに行ったが、牛乳を買うのを忘れてしまった。

BACK INTO ENGLISH

I went to the store to buy eggs, but I forgot to buy milk.