Its Not Fair

Its not fair.
None of it.
Why do 16 year old girls get pregnant and have healthy babies, while women wanting to have children cannot?
Why can one woman lose child after child?
My questions will never be answered.
I hear my biological clock ticking away, each month my chances of having a healthy baby dwindling. I know I'm only 20, and I know I shouldn't start worrying until at least 35. But with the problems I've had so far, and getting closer and closer to my peak I know things are going to be a little bit harder for me and David.
We both want a family, David wants to wait (I respect that) and I'm getting anxious. I don't feel financially ready, and I don't feel like having a baby would be met with good graces by most of my family and friends...
But I still really would like to have a baby... to know that I can carry a healthy infant to term, because right now its a mystery. We know I can get pregnant, but can my body hold on to that child for 9 months? or even just 24 weeks?