Maybe Gail is counting those lesbian/bisexual characters who have yet to be outed, like Ivy, Harley, Barbara, Dinah, Diana...
No, really. Didn't she once say that she planned on outing Dinah as bisexual but they got the wrong line and published it as "Dinah is totes straight!"? And that she wanted to include Io in a montage of Diana's possible love interests but the montage was cut out for lack of pages? So she does think of Dinah and Diana as bisexual, but technically Dinah and diana are canonically straight. I wonder how many characters are technically straight...
Not that it really matters, unfortunately. Subtext is wonderful, but it's like a consolation prize, and it forces you to deal with idiotic "just because they sleep naked together it doesn't mean they aren't 100% straight, that's just the writer joking and you are delusional!" flames.