I'm 20 and I want a baby?

Well, I feel insane asking this. Anyway, I'm a 20 year old woman and I'm in college. I'm currently single but recently I've felt as if I want to have a baby. I have no clue why. I'm only 20. It's kind of a weird feeling and it's kind of hard to describe. It's like, I want something to care for and be responsible for. I've head being pregnant makes you feel full and stuff and I want to know what it feels like. I don't plan on having children until I'm happily married so I have no clue why I feel like this. I talked to my friend who is getting a physiology major and she said it was normal and around my age you start to want a baby or something. I still feel crazy though. Someone please tell me this is normal!