have you heard of VPD ? not getting perfect VPD is the only reason i see for this result, lights are fine, distance is fine temps are fine, if VPD is not fine could be that. That or training. VPD is what regulates the metabolism of the plant, metabolism is what makes the difference in terms of growth and maturity. VPD = vapor pressure deficit , some sort of ratio between the temperature of the grow room, the atmospheric pressure, the temperature of the leaves and the humidity. Here's a chart to help you out : http://www.just4growers.com/stream/temperature-humidity-and-c02/vapor-pressure-deficit-the-hidden-force-on-your-plants.aspx hope this helps ! 🚀