What light schedule are you running at the moment?
In my experience you don't get a big gob of preflowers before you go to 12/12.... (don't know if that's the right way to say that or not)
50 clusters? Pistils emerge from a more pointy lookin', smallish looking sac at about 6 weeks into the grow...(I think)
There's not really a whole big bunch of them and can be easy to miss when sexing your plants.
Sometimes I've had to 12/12 just to find out their sex and then throw them back into veg.
Look around the forum and you can find many close-up pictures of female, male, and hermies.
BTW....welcome and good growing!!!.................J