Is it normal to be straight, but fantasize sexually about the same sex?

I am a straight female that often fantasizes about having sex with another woman whenever I masturbate.

A reoccurring fantasy is me eating a girl out while she sits on my face. Then I climax and the feeling goes away.

The thought of doing it in real life grosses me out. Not the thought of lesbianism but the thought of having a vagina in my mouth.

However whenever I am horny lesbian porn turns me on the most. Or if it's straight porn my eyes always wonder to the girls lady parts and away from the guy.

I am not gay, that's for sure. I cannot see myself in a relationship with a woman and don't have the desire to. There's just something about eating p*ssy that gets me going.

Is this normal? What is your interpretation of this?