Why am I not losing weight, and how can I improve it?

Hi guys! :-) Okay here’s my problem. I have been trying to lose weight for 2 years now… I KNOW I have a slow metabolism, but I have been trying so hard I feel like giving up. I tried for a few months eating fruits, veggies, drinking only water, and walking an hour twice a day… No Luck. I got pregnant and sustained my weight throughout the whole pregnancy and two months after I had my daughter I had lost 50 lbs. (I’m guessing from the constant vomiting) I have been trying for a year again to lose more weight by eating right, drinking water, walking, and now I use various dance videos to help with working out but I still not lost ANY weight. I am considerably overweight (although I dont want to mention how much) but nothing I do works. I feel like the only way I can lose weight is by making myself vomit since that seemed to work tremendously while I was pregnant but I do not want to have to resort to harming myself to achieve weight loss. Can anyone give me advice as to how I can lose the weight without harm and tell me why am I not losing weight after all I am doing? Keep in mind that I am very overweight so the hardcore exercises are off limits for now. I need techniques that are easy to do and follow until I start to get in better shape. Thanks :-)