that is a little wierd.
Is there any light affecting the plants night time cycle? Are there any street lights lighting up your grow area? Neighbors outside lights? If so I would unscrew your neighbors outside light if possible, or ask them to turn it off.
Some things you can do to start flowering outside. You can cover them with thick black plastic from 8pm to 8 am, bring them inside in dark room if there in pots and not too heavy.
to me it sounds like they are getting light on them somehow when they should be in total darkness. This is not always possible in your yard due to street lighting, Neighbors, Your own lighting from your inside house.
I would walk around your grow area at night to see what lights are shining. If you cannot fix that then you need to cover them in 12 hours of darkness.
The thing I am worried about for you is plants usually start flowering around Aug 15. At least they do in the Pacific NW area. So your plants should already be showing signs long time ago.
Take a few cuts of the bottoms so you can save the strain if you have not already.
To me it is just odd that you are not seeing the sex yet.
Where are you located in the World?