Relationship Status?

So I've been in a relationship with this guy for several months now. He's my first boyfriend. Or so I thought. By that I mean, we've done all the things and experienced all the feelings your everyday couple in love experience on a day to day basis. I've gotten to the point where I love him. Well, from the beginning, we never labeled our relationship. And never has he referred to me as his girlfriend. I refer to him as my boyfriend. Never do we announce us being together. He's not huge on PDA. Which isn't a problem. These things don't bother me. It's like an unspoken love. But today he asked me if we were boyfriend and girlfriend. I couldn't answer straight because it completely threw me off. What were these last months? We're always with each other and we are in love. He cares for me and treats me right. But should I be worried at all that he doesn't care to label us? I mean we're both 18 and graduated. I don't see what the big deal is.