We've only been dating for 5 months but we already talk about marriage, are we movin to fast?

We have our ups & downs just like any couplw but our families have known each other for years. Our older brothers grew up together, & thats how we met. He's always made me smile & he tells me he loves me all the time. sorry if this is too much info, but when we make love its pionate not just ....so maybe we are ready. How do I know for sure, cause he always treats me right. So how do I know?