pregnancy urge?

I keep getting these sudden urges of overwhelming wanting of a baby. I don't know why! All of a sudden it's just a huge want/need that I have, I'm craving to be a mother but I'm only 21. I mean, I have a home, a stable job and a wonderful partner (23) but he's voiced to me he doesn't want a child for another 5/10 years yet half his friends and most of mine all have kids. Why is the need for a child so strong? I've even started planning on what the nursery could look like! It's almost driving me insane.