There's no law that says women are supposd to want the family life and men aren't. Your boyfriend is probably just thinking about his future and how he wants it to pan out and since you and he are together, he is thinking about the possibility of a future with you. It might be a bit premature but I've learned that with some guys, when they get into their family phase, they get tunnelvision.
The better question is your second one: why is this freaking you out? It could be for various reasons. Perhaps you just aren't ready to make those types of commitments and even the thought of them makes you uncomfortable. And you need to know that your reaction is completely okay. Hearing somebody talking about your future together - especially after a short time - can feel like a lot of pressure.
Perhaps you don't see that kind of future with him or at the very least its too soon to talk about living together and marriage with him because you just don't know about him yet.
If anything, you should probably talk to him about it. You don't want to end up engaged to some man that you're not sure about because he's decided he wants to marry you and you are still trying to figure out where you want to live or work two years from now. Being on the same page is very important for the success of a relationship. So before things spiral out of hand, you should let him know how you feel about his thoughts and make sure that you all are heading in the same direction.
I was in the same situation several years ago. My ex wanted to get married, but I didn't feel ready, and I let him proceed with wedding plans while I was miserable the whole time. He knew how upset I was but continued with it anyway, thinking it would get better after getting married. Luckily, I came to my senses and broke everything off, and I realized that although I wasn't ready for marriage, I also didn't want to marry HIM. And now I'm in a happy relationship with a man, whom I can see myself marrying.
Gender stereotypes are BS. In every relationship I've ever been in, it's always been the guy who took things into love/exclusive/living together/marriage territory first. Every single one. And most of my girlfriends say the same or similar.
Society functions best when everyone knows what their roles are, so society tells you what you're supposed to want so that you'll fulfill that role. Sadly, people are individuals, and they'll want what they want and there's nothing anyone can do about it. If what they want doesn't fit the mold, they get confused and scared, like you, and have no frame of reference to draw from.
Anyway, in the end, you have to go after what you want and not get dragged into what you don't want. Don't worry if you're not adhering to your gender role by wanting to be remain a single woman for a while- there are more of us than you think.