Re: High dose triphala, lactulose, chlorella doing little for constipation.
Something you should take into big consideration is carbohydrate to protein ratio. I have spoken with many cattle farmers and they take carbohydrate to protein ratios very seriously as changing these ratios will greatly impact the bowel movements and hence the intestinal health and milk production of the cows. They try to get somewhere from 15-20% protein for the cows, anymore protein will cause constipation, less protein will cause diarrhea. The ratio for humans may be different but maybe not very different. Generally, the more protein you consume, the slower digestion will become. Animal proteins will sit in your stomach longer than any other foods and will continue to move more slowly through the entire intestinal tract. Diary is even more constipating and cheese would be the most constipating. Carbohydrates will move through the stomach and intestines more quickly, fruit moves the quickest of anything. So if you are eating meat and veggies you are doing the opposite of what you want to do. I believe you said it didn't really seem to make a difference what you eat, then I would say eat a high percentage of carbohydrates in your diet, especially fruit would be great for you (as long as it doesn't cause any problems). You say it doesn't make a difference what you eat, okay so fine maybe eating more carbohydrates won't solve the problem but if you continue eating a good amount of carbohydrates over time and take a very good herbal supplement to help the bowels move, this could be a very good combination to help correct your problem over time.
Anywhere outside of India Triphala will be ridiculously expensive which is silly because it is just made of three fruits that are not expensive to grow at all but I guess they only grow in certain climates so most places in the world cannot grow them. I don't think it is a good idea to supplement with magnesium long-term, not sure about lactulose but I think this could be problematic also as it draws water out of the bowels and could mess with electrolyte levels. Chlorella is known to cause gas and diarrhea which is not what you are looking for (could be useful in smaller doses). You want well-formed bowel movements which maybe is not possible for you right now, but they should at least be somewhat formed, if not you need to stop what you are doing and try something else.
What is causing your problems? My guess is that it is the bacteria in your intestines being out of balance. You said when you eat large amounts of yogurt it helps your bowels move properly, this is because it is being loaded with beneficial bacteria that is temporarily correcting things but these usually don't colonize the colon and in large amounts they can make things worse. I would say you can eat one serving of yogurt per day and it should be helpful for you as long as it doesn't make things worse. Some people say to take probiotics as a supplement but I am not a very big fan of this as we don't really know what the effect of taking large doses of progiotics is on the intestinal population. I know in cases of SIBO, taking probiotics will make things worse because the bad bacteria uses the probiotics like food and just gets even worse. I still think the best way for you to correct your problem is to take some sort of natural herb that stimulates the movement of the intestines. You will need to find something that helps you get bowel movements that are at least somewhat formed. Whatever you take you will probably have to take very large doses so it will not be cheap but when you take it over time this will help the intestines clear out the bad bacteria and naturally repopulate the good bacteria. It will not happen quickly, it will take time. So eat a high percentage carbohydrate diet (healthy carbs obviously), eat serving of yogurt every day, take a natural herbal supplement, take enough so you have a least one bowel movement a day that is at least somewhat formed, if whatever herbs you are taking are not giving you this result keep changing herbs until you find one that works.