Don't listen to Frost down there.. All seeds won't be female.. There's a high risk of hermaphrodites. Which is why breeders don't use stress to try and make feminized seeds anymore.
- Good news is that your plant pretty much only have withered pistils left, so if trichomes are the colour you want, then it's time to harvest anyway.
If the trichomes aren't the colour you want, then add a drop of water on the sacs, and gently pull them off with tweezers, so you don't pollinate anything. Don't add so much that it runs into the bud tho, you don't want to risk mold.