I think it must be a generational difference. They grew up differently. My mother would think the same thing. I'm 99% positive. In high school, I told her I was bi just to make her mad (hey, I know - not nice).
I've had ... what I would call "crushes" on girls. It's been an attraction, but I can't say it was sexual. I don't know what that makes me. I've made out with girls, and it was fun... but never with one of those "crushes." I don't know if my reaction would be different if it had been. But the fact that I never sexually fantasized about them always left me wondering what the heck that makes me.
So, no. You're not alone