Hmmm.. Oxypowder will liquify stools but only at first because it oxygenates them. After awhile the stools just are a bit soft. Triphala is different. It is a laxative, pure and simple. It also does tons of other good things to the bowels, but it's not good to take so much that you get liquid stools. To exercise the bowels yet keep them in the right shape, stools should be formed. So only take the dose that allows you to have formed stools.
If you've been taking it for 3 months, now would be a good time to stop taking it altogether and do a "reality check." See if you even need it at all. Just about all supplements and interventions should be temporary.