3 pouches a day doesn't sound excessive to me. That's what Jaffa has (plus dreamies twice a day) and he maintains his weight on that even though he's an older, indoor cat who doesn't take a whole lot of exercise. Mosi has half that amount with the remainder made up with biscuits. He is more active but also maintains his weight (I consider biscuits to be more "fattening" than meat so he probably takes in more calories than Jaffa).
What wet food are you feeding? Does it contain cereals/veg deriviatives? If it does, I would consider buying one without as cereals, soy etc. aren't ideal for a cat and make a food carbier which, imo, will not help with weight loss. carbs tend to = weight gain for cats.