Have some patience... I'm pretty certain she'll start showing herself to be female soon - but it really IS too early to tell. Some autos go into pre-flower in week 3, but I've had ladies that don't go into pre-flower until week 6 or 7 - and some have gone from what YOURS looks like right now to rather "instant" flowers... Just be patient - she looks like you've done a magnificent job so far...
Good luck!