3 weeks into flower and almost no buds

Dear, oh dear! With all your technology and great set up, you have fallen victim to a basic and fundamental principle in plant botany. Stretching after going into flowering or 12/12 is completely normal. Flower size after 3 weeks being the same as it was at 10 days is not normal and basically, your fault. No other way to put it, sorry. Plants rely on photosynthesis to grow. Photosynthesis occurs in the leaves. Heavy defoliation has caused a massive reduction in the amount of energy your plant can produce, therefore slowing/stopping growth as you have experienced. Less leaves = less energy = less growth. OR More healthy green leaves that the plant has = more energy production = more plant growth. At this stage there is nothing you can do but wait for your plant to grow new leaves to then make the energy she needs to keep growing her flowers. Unfortunately, this means flower growth will be slow and no doubt smaller than to be expected, due to the plant having to "divide" whatever energy she still can produce, between leaf growth and flower growth, with both receiving sub prime amounts of energy to successfully do both at the same time. Defoliation is a bad thing at any time in my opinion, but the absolute worst time to do it, regarding plant health and function, is during flowering. The only leaves that should, in my opinion, ever be removed, are the yellow leaves, for by the time they are yellow, they have served their purpose. Nothing but patience is going to help you or your plant at this stage, just keep this in mind as what not to do in your next grow. The leaves you removed were also a ready source/bank of pre-made nutrients, like carbs, sugars, amino acids etc that your plant would have drawn upon during flowering, as it is more efficient to do so, rather than grow flowers AND make these elements from new during flowering. So, not only has defoliation stunted your plant by reducing her ability to produce energy, it has also robbed her of this vital "stash" of pre-made growth elements that she has so cleverly stored in her older leaves, precisely for use during flowering. This is why the older leaves will go yellow ("the fade") on otherwise healthy and well fed plants during flowering. So by defoliating heavily, your plant has suffered a triple whammy to whatever energy she is still able to produce, and this lowered energy amount must now be divided between trying growing new leaves, trying to grow flowers and trying to make new amino acids, sugars and carbs etc to power the growth of the flowers and leaves. At least you now have first hand experience as to why I and many others are opposed to defoliation. There is nought you can do, but continue with your care routine and be patient while the plant struggles to flower with her diminished capabilities. Hopefully she will not suffer any sort of major "metabolic shock" due to the sudden and massive drop in energy production, shock that can instigate hermaphroditism due to the wild swing in hormone levels experienced by your plant, causing it to possibly "freak out". Sorry if my answer may come across as harsh criticism, but it is what it is and a stunning example of why defoliation is ill advised. Think of it as an "defoliation intervention!" I wish you the best of luck, but hope my unsympathetic and somewhat harsh reply will encourage you and any others that read this, to think twice about defoliation now or in the future. I am however a bit of an anti defoliation crusader, 35+ years of growing has taught me that removing healthy, green, energy producing leaves, is really not in the best interest of the plant. Cannabis has evolved to grow her biggest and best flowers. Getting rid of perfectly healthy, green, energy producing leaves for no reason or benefit, is not part of that process. Hope this helps,............ Organoman. (and vehement anti defoliation advocate!)

Be patient man. It can be nerve racking this growing game but most of the time theres an explosion of growth in the last few weeks. Good luck