Fat stems plump buds?

You have killer lights. Its really just making the perfect photosynthesis. Light, nutrients and co2. Have you looked up VPD. Or you could try a negative pressure environment I've had much better results this time by just changing that 1 thing. To hit optimal growth you need to relax on overfeeding. See the way your leafs are all curling under. Usually related to N tox and your plants are very green. But it's not to bad I don't see any clawing or you don't have a shine. Relax on the feed have a look at dual part feeds there's lots out now where you can give grow and boom together in ratios of 3:1 so say it works out .3ml/l grow to .9ml/l bloom for when they are flowering and turn that on its head for growth. Jungle juice trio is a good line 3 1l bottles G,B,M for 24e or a dual part grow, bloom & micro from general hydroponics. It'll stop you overfeeding with grow as the pk from the bloom helps nutrient uptake so look into dual part feeding. Also uppotting will help make for a strong root structure (root ball). So some ppl uppot up to 3 times to make for strong roots. Anyways there's lots you can do to make for stronger growth, bigger buds. You have killer lights, id say the ppfd is huge so it has to be for ventilation and you need to keep bringing in co2 by way of drawing in o2 or use a co2 supplement but a negative pressure environment will help increase co2 and make for denser buds. Good luck.