This is why I hate autoflowers!
Not much can be done size wise, she will take 6-8 weeks to flower and be ready for harvest, and you might be lucky to get enough for one joint.
Trichome production is controlled genetically and you can only ensure healthy growth to encourage healthy trichome production.
Autos need 18 hours of light for best growth and generally perform very poorly outdoors.
Try growing some photoperiod feminized seeds, then you will get a proper yield from proper plants!
Hope this helps,............
Organoman.