How do you know..

I've always liked the female body and les porn. I've never been with a female in any way but yesterday at a night club I seen a beautiful girl like seriously she was gorge. She told me I was beautiful.. something I've haven't heard from anyone in a long time so I told her she was too. She asked me if I liked girls I told her "I don't know" she told me "that's ok because I know I do" We danced and got real close and personal. After yesterday I've just been thinking am I bi..? Like how does one know if youve never been with a girl. Ive been thinking about this way before the club situation...