Use your hermaphroditic pollen sacks to pollinate some of the smaller buds from your girls. The resulting seeds (if you are lucky enough) will be feminized (all girls) when they sprout. You can apply pollen with a small paintbrush and keep the rest of your buds safe. The only danger here is that if your plant is a hermie because of stress (light interuptions, disease earlier in life, etc...) then the resulting seeds may be either weak or produce more hermaphroditic seeds.