I think your container size is too big.

There is the root to shoot thing, where basically things will grow much faster if you start off in say a 2.5 inch pot...then when roots are showing out of that, transplant to 3.5...then 5.5 ect. Recently I tested this out. I used to just go from a grow plug with roots showing straight into a 3.5 wide x 5.5 deep square pot. I got 800 ( for about $ 60) of these smaller ones 2.5 wide, that are still very deep and have been using these now as a first step. The ones that have gone into the smaller and been transplanted are much bushier and have grown faster.

For me, I veg them in the 3.5's until they are about a foot tall, keep them in the same container, prune lower branches off...put in F zone and then transplant them into 5.5 or 7 inch (wide, square) pots for the last 5-6 weeks of flowering depending on when I get the time. I have finished plants that ended up being 4 ft tall, and producing 20+ grams....in the 3.5 container. I find it easier to transplant to the larger size so they don't tip over as easily and it doesn't worry me if I missed a day of watering/feeding which I regularly do every other day.