You sound as though you are addicted to Stevia. There are a number of articles out there which bash Stevia as dangerous. The FDA does not seem to be very positive on it and warns of the potential for cancer. Now someone may argue that almost anything and everything can have the potential to cause cancer.
In my opinion you should definitely not take Stevia during the cleanse. It might be that it's stopping you from losing weight and it sounds as though you are not going through any detox symptoms. You might also not be losing any weight because your body has gone into starving mode.
I am also into day 10 and have also lost only 5 pounds, though I am doing it more for the general health benefits than the weight loss and am not overweight per se.