Did you plant her late? I've got a very similar situation with a plant that I started late.

I would think if this plant of yours was going to be male it would've shown its sex by now. Females tend to show up later in the game then males from what I've heard. Out of my four plants, the males already showed up (2-5 weeks ago) and were promptly eradicated by yours truly. I haven't visited the remaining plant for a couple of weeks, but last time I was out there it looked just like yours. I'm pretty sure its a female since the males were already so obvious (and the odds are in her favor given that 3/4 were male).

If she takes much longer to show I'm going to have to start worrying about a freeze before harvest though...