Is it normal that i pretend to be with people i know when i'm not?

I'm a seemingly normal guy (but I'm a bit quirky to be honest) with above average intelligence; nothing too intense. Most people like me, but I'm bipolar, so I am usually being fake. I'm actually relatively antisocial and interact socially mainly for my ego, but sometimes it can be genuine. When I am alone, I imagine that I am with the people I see pretty often; usually girls I'm attracted to or guy friends I'd want to impress. I talk to them in my head, and it's almost like they watch my every move which, because I am alone, is natural and therefore reassures me and my confidence. But I am naturally arrogant sometimes, and have low self-esteem at other times. Basically, it's like I hang out with my imaginary friends except they exist in real life. It's almost like an imaginary world I live in. Sometimes, I relive situations with them that maybe I experienced that day with them or even in the past. Is this normal? Does anyone else do this? If it helps, I am also obsessive-compulsive.