I have trouble telling when to use "il mio" and when to use "mio" without "il." Could someone explain it simply? Thank you!

See a translation

"Mio gatto è in la cucina" is wrong.
My explanation wasn't that good I think. Honestly it's hard to say "in this case you put/ don't put [il]".


However:

Il mio gatto è in cucina.

You have to use "il" because you're talking about "your cat" not a simple cat, and there are a lot of cats.

Now I was thinking that we use "mio" without "il" just in a few cases like:

My father/ etc (family members)
Oh My God! (Mio Dio!)


When answering we use/don't use "il".
Like:

Whose this?

È mio / È il mio

Both are used even if "È mio" is more common.




So, to sum up, always use the article if you are talking about something different from your family members.
Pay attention that "My family is big" needs "la":
La mia famiglia è grande/numerosa.