yea i don't think its gonna double or triple in height these things are huge already. if youre in californiawe don't get true 12/12 until September, in late august we'll have like 12 and 45 mins of light per day. if they're 10-11ft tall now i would guess they will end up at 13-14ft when all is said and done.
ive seen 1 lb plants and yours are alot bigger so im guessing youll past the 1lb mark per plant with ease. i dont know how much you smoke but even if they were just 1 lb each and you have 15 plants = 15lbs. thats insane for personal grow haha. good luck with the rest of your grow.