Looks like you defoliated too heavily. That would be part of it, but mostly genetics. the defoliation reduced it from genetic potential. not all plants can grow donks.
I can see through your canopy, so a ton of light never hit the plant.
Scope the trichomes to determine a consistentn harvest window - that way you can test different points early to late and determine what you prefer with the least amount of trial and error. 10% amber? 80% amber? something between? It's fine to read what others feel on the subject, but in the end it may effect your body slightly differently than someone else's. In general, the more amber you see, the 'sleepier' the high will be.