Just to add - based on your last post above - you should not increase to get that “feel good” feeling. You might get euphoria on occasion, especially when you’re new to Kratom, or take big breaks between doses, but that isn’t going to happen every time.
Try to expect subtle results, and if you get more than that, it’s a plus!! Like real opioids, trying to get that feeling by taking more and more (chasing the dragon, or maybe iguana in this case!) is how you can get addicted to it and have a 50gpd habit that’s hard to cut back on or stop.
All the advice above is good. Get the scales, rotate your strains, use multiple vendors, cut your dose (especially most TFH), and I would also suggest sticking to 3 doses or less, unless you’re using for severe chronic pain. We’ve all been in your shoes, so hopefully this can help you not make the same mistakes.
Regarding TFH, I have found that I had to cut my usual dose in HALF compared to good quality Kratom I buy from other vendors recommended here. I’ve used for psoriatic arthritis pain daily for three years, and use multiple vendors, and was shocked at how much I had to reduce my dose with TFH