I'm sorry but there's no way Fluttershy is straight despite her rampant homophobia.
I will post the evidence here.
>Gripped Twilight's ass like this during the hug
>When She was stuck in the porta potty with AJ and Twilight she lied about them doing sex stuff
>She dances in a bikini sexually for other mares
>When Fluttershy beat up Pinkie Pie in the bathroom she was going to make her dance for her sexually
Fluttershy is not straight.