Year and a half.... Weight loss zero?

I've been trying for a year and a half to lose weight... And I've tried every diet under the sun. Atkins, weight watchers, slimming world, cabbage soup the list goes on. So I changed my mind and started to change my eating habits to see if this would work, but to make dismay nothing happened. In conjunction with this I go to the gym 5 days a week go swimming once a week go running 3 times a week and do Zumba 3-4 days a week.... So I can't see why I'm still 15 stone.... I haven't lost or gained weight but it's just not shifting... I am living at the moment on chicken with no fat or skin vegetables, I have pasta with tomato sauce (brown pasta) and I eat a lot of fruit and vegetables. I don't has takeaways.... So can someone tell me what's wrong with me, because I just can't do it anymore..... Dieted and exercises and failed miserably