Nutrient feedings probably are not up to par, i noticed pass grows my buds were tiny, i like you was using 600 grams to get 21 grams of bud from 3 plants with 6 week vegg, it sucked, lucky me that i had an extra plant outside that i practiced in dialing in my nutrient feeding. I see a super huge difference and that plant same strain had only a 3-4 week vegg and looks like it will yeild 2+ oz and the buds swell bigger than i ever saw. Since than i keep my Ph level at 6.5 and feed accordanly as my religion.