Serious problem with small buds.

First, expect more bulking of buds at top.. even if your concern is real, you'll still have plenty of fine buds, but a larger proportion of larfy buds.. a spectrum really and shifted a bit toward larfy compared to if you had a few less colas per sq ft. I don't think it's anywhere near as "too much" as you might currently fear. Looks generally okay, but maybe a bit overpopulated in some areas. Canopy receiving/absorbing all of the light provided is the most important factor for yield There's a point were more colas per sq ft doesn't improve yield but does make buds smaller throughout canopy. Genetics matters. Some plants grow donks, others do not. the plants that naturally grow donks probably don't need as many colas per sq ft as a plant that does not grow donks. familiarity or at least some insight into this likely trait would help greatly in planning how many colas per sq foot to target. i can't find the url, but cocoforcannabis came to the conlcusion 2.3colas/sq ft was optimal. I would wager the points about genetics makes this a bit volatile relative to any 1 seed planted. This sounds reasonable... Excellent full coverage of canopy and excellent light penetration / air flow etc (though ATP is extremely mobile, and apical dominance is primary factor for the level at which larf becomes consistent or expected)

Don't worry, looking at your flowers you have a good 4 weeks left if not more then that. Everything looks like its doing what it should do.

I think it's a little early for worrying. You got a full space but I don't think you're overcrowded. Some strains pistils brown sooner than others(especially if you maybe brushed against them while defoling)and you're right at the stage of flower where swelling truly begins to start. Growing in only hydroton, I would probably increase the frequency of your irrigation vs increasing nute levels, I'm not seeing signs deficiency really but, like when using coco, frequency of availability does affect bud growth. Your overnight temps a little low, some strains are more hearty to cool temps than others.