How come it's "ok" for women of different ages (married or not) to get pregnant and have babies but...

I'm a responsible 25yr old, have a degree, small bills, in a 2yr relationship. Why is it that when I want to try and get pregnant, everyone tells me to wait. The 16yr old girl in high school didn't and she turned out fine. Halle Berry had one and is fine. Young couples in college have babies and it seems like they doing fine. So why should I have to wait until I'm married or close to 30yrs old to have a baby and experience all the joys it brings...Don't you know most people die when they are between 70-80yrs old, it's not like i have all the time in the universe?