YOU SAID:

If I get a cat then I would get multiple cats.

INTO JAPANESE

私が猫を飼うなら、私は複数の猫を飼うでしょう。

BACK INTO ENGLISH

If I have a cat, I will have multiple cats.

INTO JAPANESE

私が猫を飼っているなら、私は複数の猫を飼うでしょう。

BACK INTO ENGLISH

If I have a cat, I will have multiple cats.