Worm castings are not really a fertilizer but more of a "tonic" and as such will not provide macro nutrients for growth, you will have to increase your feeding - Bio Vega and Bio Flores made by Bio Canna are excellent organic nutrients that work extremely well.
Organic Grow and Organic Bloom made by B.A.C. is also good.
Adding some soil mycorrhizae like "Mykos" from Xtreme Gardening will also help tremendously with over all vigor and health.
Also, some humic acid, fulvic acid and amino acids will really get the party started and are organic too.
As a side note, try and limit any defoliation to only any yellow leaves, your plant needs all the healthy green leaves it has to make the energy it needs to grow its biggest and fastest.
Defoliating autos is a big mistake in my opinion, or any plant really.
Just remember -
Maximum amount of healthy green leaves = maximum amount of energy production = maximum growth.
It really is that simple.
Less leaves = less energy = less growth.
Also, 18/6 is much more cannabis friendly, cannabis Needs sleep and 4 hours just is not quite enough.
You will not lose anything by going to 18/6, in fact you will probably gain much, due to the plant having a healthier metabolism.
Hope this helps, Organoman.