Hey man, cool journal, just sorry I missed most of it!
I'm also trying some photos for the first time so on a massive learning experience.
Now, I am not very comfortable offering advice as I am not experienced, especially with photoperiods. But we share a friend in Sir Ryker so he will tell you I would only try to help, and not pretend I know everything.
Having read through your journal twice, a couple of things stood out that COULD partly explain your disappointment with plant size/yield etc. I do have experience with cobs so that MIGHT help a bit!
First thing, I personally think you had too much light during vegetation, or maybe the cobs too close? In pretty much all the veg photographs I see tacooing of the leaves, which can be a sign of too much light? Also looks like the plants are generally very short and stocky, with close internodes? Both things could be a sign of too close lights/too much?
I think to get more yield you could maybe train them more aggressively in the stage of vegetation when you see them really get vigorous. And after topping / fimming. Thats when bending the main stem over (fimmed ones) and tying the plant outwards (topped ones) seemed to have the best effect on my plants. Also leaf tucking all the way through veg really seemed to help my plants. Once the growth tips are exposed to direct light they just want to become colas naturally it seems? Again just my experience on my first photo grow.
I got some very similar looking yellowing of lower leaves in early veg when my PH pen was reading incorrectly and I was feeding them at 5.3 PH! Doh! Do you check your PH? I know you don't really need to, but worth a try maybe?
Again mate please don't take this as me knowing everything and telling you what to do! I am learning at the same time as you, and have made some juicy fuck ups along the way!
Anyway dude, they all look really good and you're gonna get some awesome buds in a few weeks so don't stress about it. It's all good
My final bit of advice would be to ditch those crappy nutrients and get yourself some Biotabs!! Speak to Ryker