Yeah it could be the strain you have, But you can start adding molases 1 tbl spoon per gallon per watering in 12/12 and that will make a HUGE difference.
Use wood ash during last two weeks of flowering.i was woundering how people get those nice rock hard, dense popcorn nugs? i have a 400 watt hps, great ventalation, and temps at 74, and i can never seem to get them nice dense bud.
Have fans blowing air down on top of your buds will help I use clip fans .