Yellowing leafs and buds not growing

Buds are barley growing I’m in week 5 of flowering and buds seem to be coming on quite slow, and some of the leafs towards the bottom are going yellow, what can I be doing wrong please help, using biobuzz all mix soil with a drop of bio grow and 2ml of bloom per water, a 600w mars hydro led grow light about 12 inches away from the plants

Im currently on my first grow, so im no proffessional, I'm unsure of the pace of bud development, but what I can say is the it's normal. Plant is using up nitrogen stored in the leaves to develop bud growth. They will eventually die and drop off.