Could my boyfriend be gay?

I'm thinking that my boyfriend could be gay? It seems that he ONLY wants to have doggiestyle position sex. I never let him go in anal so he goes in vaginally. Then when I go over his place on the weekends he spends 3 to 4 hours on the phone with his male friend playing video games. He also go out with this male friend to the movies or events during the week. One time I called his place during the week and he went outside just to talk with me on the phone 11:50 at night. I asked him why would he step outside to talk on the phone late at night when he lives alone. He said if he wants to do that he can. It seems that every time I go over his place he is constantly in contact with this guy. Now I'm wondering why he only like to have sex doggiestyle and in no other position with me. Does he sound gay? I asked him if he is gay but he just calls me crazy.