Damn..You must've got a good seed if you can grow something like that outdoors with no chemicals/ferts/nutes. That's a good resin production rate cause that looks like its been in flowering for only about 2-4 weeks at my guess, am I right? At this rate your buds will be frosty as fuck by the time its done..I'd estimate another 3 weeks atleast..If you really want to help stimulate those colas i'd look into lollipopping, because I feel like those colas would fill in really nicely if done properly.
Happy growin hope that helped