Please post your stats again, not positional. general PT stats. I was struggling for 2 month myself after having a huge downswing at 100NL. Maybe I can help. 27k hands is a small sample and could be variance. You should be crushing 25NL with 18/13/4, but maybe you have some postflop leaks.

Below is my graph since July. After running bad, I went on tilt and played suboptimal. changing my game, getting nittier, less aggro, giving up to fast postflop, playing predictibel etc ... wich resulted in loosing.