Why do I all of a sudden want to be pregnant?

I'm 20 years old and am no where near ready to have a child. However, I've been dating this guy who I like more than any other guy I've dated. We're getting serious and it's all so exciting for me. We have the same views on having children which is cool, but neither of us want children at this moment in our lives. I have been having dreams/day dreams about being pregnant with his child. I've been almost craving being pregnant and I have no idea why. My dreams are so vivid. My full term pregnancy to the actual act of giving birth. This is crazy!! Is this a chemical reaction when you're falling in love with someone?