After surgery, individuals loose weight at different rates. The three most important elements after RNY gastric bypass surgery are to meet your daily protein, fluid and vitamin requirements. Food is secondary because your body is converting your stored fat into the energy that drives your body. Thus you lose weight. So adhere to the program guidelines.
Since you are at 3 months, there is one thing you might try if you haven't already.
Your daily protein requirement is met by a combination of the amount of protein you obtain from food combined with the amount of protein from protein supplements (protein shakes, protein bars). Right after gastric bypass surgery, the volume of food you consume is minuscule (2 ounces) per meal. But as you get further along, the meal volume increases. Therefore you have a very important option available to you. As a result, you can begin to reduce your reliance on protein shakes. I went from 3 a day, down to 2, down to 1 and eventually none when I reached 1 cup per meal at a year and a half post-op.
This is important because protein shakes contain calories. If you can reduce your caloric intake, then you can end a stall. At least that was the approach that I used and it worked for me.