you won't get more calyxes growing - just existing ones fattening up the rest of the way.
this is mostly genetics but can be due to growing methods too. e.g. an over-crowded canopy will have more stretch than if it wasn't. A plant with too many colas per sq ft will also tend to have smaller buds. Per genetics and assuming competency elsehwere, there's really no way to circumven the ceiling of grams per sq ft (realtive to ambient or supplemented co2). Some genetics might top out higher, but that's not in our control. More is not necessarily better when it comes to branching / number of colas per area. If you can max out yield with just 2-3 colas per sq ft, that's all you need.
i don't think your canopy is over-crowded, but sure seems like some excess stretching occured. It could be genetics or self-inflicted. if you stripped off fan leaves, this can also cause needless stretch. Defoliation is a bad idea unless there is a specific reason to do it. not some vagaue broscience 'it helps the plant focus on buds' type conjecture that is not and never was based on any evidence.
"supposed to be 9weekers" that's all fine and good, but what should be is irrelevant to what is. Genetic variety, again, will be a huge impact on this even if it is the same strain. Observe and react.. .time will tell if they are 9 weekers. Maybe, one finishes in 52 days and another in 65. These are not things within our control. You just patiently let them happen.