Hi any help greatly appreciated these plants(9) are 2 weeks into 12/12 Under 4 x 400w hps pineapple chunk pink Kush gorilla Zkittles temps are 29c lights on 20c lights off feeding Biobizz Grow, Bloom, Alg amic

Hello everyone! I have been nuturing a small sativa for a while now and it hasnt been a smooth sailing to say the least! I have some questions that perhaps someone here on the forums could help answer. . . So first a bit about the little baby: its a small pot plant grow, diameter +- 10-15cm, depth +- 15-17cm (so its small) started with a ultra-crap compact soil (from garden center) for seedlings. not much in the way of nutrients in there sprouted around August it has been through some cold weather and dry spells I fed it with some worm castings mix (very lightly though) I transplanted it to better soil ("herb" soil which is light and fluffy with slow release nutes, i havent subsequently fed it) and I added vermiculite too I topped it around 1-1.5 months into veg stage (it had 3 nodes when i did) it has been into flowering now for around 17 days & has formed 2 nice little, little, tiny buds My aim was to have a small patio grow with maybe enough end product for a couple of smokes. Nothing hectic. So the issues started happening when I had it in the crappy 'hard' soil. It was not draining much and I suspect it developed some root problems there. So I transplanted it to the fluffier soil with added vermiculite. It seemed much happier. That was about 3 weeks ago. Now, I am seeing the old growth (bottom leaves) going yellow, curling downwards, and the leaf tips starting to decompose moving inwards. Take a look here: Notice the curled leaves... Here are some shots of the plant as a whole: So I am thinking this is a Nitrogen deficiency but im not 100% sure. . . & i dont want to add any if its not needed. Also the possible root damage might be an issue too. Another thing I can think of is that the plant is using up those leaves to provide for the buds? Not sure. . . Does anyone have an opinion as to what may be causing this? Thanks alot guys!!!