Tomatoes can take a while to turn red. So long as the plant isn't showing signs of distress, let nature do it's thing. I've had fruit ripen within weeks, but I've also had it take months. The weather can play a big part in this. Heat, water, sunlight, and more can change how your plant progresses.
ok a few factors that can affect tomatoes not ripening a few you have covered, to low or fluctuation temperatures can cause them not to ripen, not enough sun light or air circulation. BUT one factor if power feeding you may be triggering too much foliage growth excess foliage can cause tomatoes not to ripen, the other factor is wrong soil PH can also cause the tomatoes to not ripen.
so here are a few tips to try to force ripening , shade the plants cut back the available light buy 25 to 50 % with shad nets, cut back the watering, and or make sure to removes suckers where main stem meet the stalk, prune back the growing tip of each branch. these tricks all trigger the plant response to think i am dyeing i need to ripen to propagate the seeds mass.
But my gut feeling if you are power feeding you have too much nitrogen hence will have an excess growth of foliage because if the plants have surplus nitrogen they will divert energy to leaf production the big factor people make for mistake is over feeding at most you should not need any more the 2 maybe 3 feeding during life cycle of plant unless soil is extremely poor. Another common direct plant related issue that cause a plant not to ripen is too heavy a fruit load more tomatoes on plant then the energy can supply to ripen this can be cause from not pinching back suckers they for extra blooms that set fruit or just general pruning to control amount of fruit that set, you can take 20 to 25 % of the largest and put them in a box with an apple sliced in half or a ripe banana and set on plate on top of tomatoes the Ethylene gas will act as a trigger to help ripen the tomatoes you picked those left on plant should start to turn after you reduce the amount on plant if that is the issue