YOU SAID:

I bought a cat on my birthday and than it ran away a year later on my 15th birthday

INTO JAPANESE

誕生日に猫を買って、1年後の15歳の誕生日に猫が逃げた

BACK INTO ENGLISH

I bought a cat for my birthday, and one year later, on my 15th birthday, the cat ran away.

INTO JAPANESE

誕生日に猫を買ったのですが、1年後の15歳の誕生日に猫が逃げてしまいました。

BACK INTO ENGLISH

I bought a cat for my birthday, but one year later, on my 15th birthday, the cat ran away.

INTO JAPANESE

誕生日に猫を買ったのですが、1年後の15歳の誕生日に猫が逃げてしまいました。

BACK INTO ENGLISH

I bought a cat for my birthday, but one year later, on my 15th birthday, the cat ran away.