YOU SAID:

the shoes i was going to buy went out of stock in my size

INTO JAPANESE

私が買おうとしていた靴は、私のサイズで在庫切れになりました

BACK INTO ENGLISH

The shoes I was about to buy were out of stock in my size

INTO JAPANESE

私が購入しようとしていた靴は、私のサイズでは在庫切れでした。

BACK INTO ENGLISH

The shoes I was about to purchase were out of stock in my size.

INTO JAPANESE

私が購入しようとしていた靴は、私のサイズでは在庫切れでした。

BACK INTO ENGLISH

The shoes I was about to purchase were out of stock in my size.