Most of the leaf stems are red and i can see it et...

Difficult to say for sure because you have stripped all the lowest leaves which would have given definite signs of which deficiency if any you are dealing with. Your upper leaves aren't really showing signs of deficiency. I agree with Spinner Caribbean your leaves are very dark green. Once in bloom your plants use less nitrogen if you keep adding it and the plant is not using it build up of this element could lead to the dark green leaves. Dark almost blue green leaves and dark blotches almost black with red stems is also a sign of a phosphorus deficiency. In terms of genetics red stems could be a trait of this particular breeders strain each seed contains different percentages of each trait. Also night time drops in temperature can bring out reds and purples in stems. While the red stems are a sign of phosphorus deficiency it is also a sign of potassium,magnesium and sulfur deficiencies. Back in week 5 your plants were showing signs of a sulfur deficiency. Yellowish leaves with red stems and purple streaks running up the main stem is a sign of this deficiency. You mentioned having soil ph issues I would suggest doing a flush with plain water with a ph of 6.0 to 6.2 then read the ppm and ph of the runoff initially coming out(First run off) This will give you a good idea where you stand. While using the runoff from your pot will only give you an approximate idea of the soil ph keep in mind that if the water goes in at 6.2 then comes out 5.8 you have a 4 point difference this means your ph is actually lower probably in the 5.4 range which is a potential cause for the lock out. If the run off is over 1600 ppm I would flush to get it down into the 1000 to 1100 ppm range. Then the last quart of water use your normal nutrient routine. Let her dry out a bit before her next watering. I would concentrate on giving her a flush then concentrate on bud building by continuing your nute regime adding the Kool Bloom to give her the extra phosphorus and potassium. You can try to adjust your future feed /waterings ph to 6.2 to 6.5 and keep checking the run off. Hope this helps to be honest I don't really see any major issues other than a bit of potential ph lock out.👍