Get some giberalic acid (im not sure where to get it, though you might try a hydroponic store or nursery) and spray it on one branch for a week or two every day. eventually, male pollen pods will appear on that branch. use the pollen from there to pollinate just a few female flowers (you only need a few seeds, so keep the rest for sensimilla) the resulting seeds will make only female plants, so when they sprout you can just keep taking clones while the plants are vegging and you'll be sure that the clones will be female as well. no more guess work!
