Is it true that everyone is a little bisexual?

I am a woman. I've always considered myself straight, but lately I've had both sexual dreams about men and then sometimes sexual dreams with women. In both dreams, I am aroused. But mostly with women I am aroused when I kiss them or touch breasts...I'm actually a little repulsed by going down below the waist area. Is that normal?

Would it be true that sexual preference is more on a continuous spectrum rather than one side or the other?