Hi Im Having Problems With My Weight Im Only 5.4

hi im having problems with my weight im only 5.4 and weigh almost 12 stone but for what i eat i most definatley shouldnt be this size, i very rare have bread and dont take sugar in anything, im not intrested in chocolate so my intake is very small really, im always cautious of what im eating due to my weight, i exercise regular doing things like 30min dvds that are intense hit training. i have had my thiroid checked at the doctors who say its fine. My other problem is that i have stomach problems so i can go weeks where im ok then something as simple as a salad can cause me to bloat and have gas and the symptoms last for upto 2 weeks. i just feel at a loss with everything i try to do to loose this weight. im 34 years old and have always weighed 9stone upto having children but they are now 4 and 6 years and i eat healthier now than i ever have done before.