Is it normal that my only friend is my boyfriend?

I'm not clingy or obsessed with him. I have friends, just not ones I hang out with. I've never had close friends most of my life. Is it normal to consider him my best friend? I only hang out with him (and sometimes his friends and brother when they are there), and I have no problem with it. Is it healthy? Again, I'm not clingy or anything, nor do I get jealous or mad when he hangs out with his friends. I'm actually happy when he does, and I do enjoy my alone time. I'm a senior in high school. I'm not depressed or lonely. Comments appreciated (: I'm just wondering if this is normal.