I'm going to give you the view from the outside of this. You can take it or leave it, of course.

Having sex is not a sign of maturity. Anyone who has gone through puberty can have sex. Anymore, that means that people 10, 11, 12 - and they are not mature by any stretch of the imagination.

Going on vacation is not a sign of maturity.

Maturity is about being independent and able to stand on your own two feet. Someone living with mom, whether 12, 17, or 53, is NOT mature.

Once you move out on your own, get your own place, and have a job with which you can support yourself and any child you might create, then you are, arguably, mature. Until that point, you are immature and simply think you are mature.