Doing weights are necessary because we lose muscle mass every year starting in our twenties so you are doing right by incorporating some weight training. We need muscle to burn fat. You need cardio too but not every day (unless it's walking as it's low impact) same with weights not every day but every other day. 2 or 3 times a week is fine.
So if you are eating right and eliminating fattening/sugary foods AND exercising, don't worry about what your sclae says, you will start to see results. Also, our weight fluctuates thru out the day, and its up and down. Your true weight is what the scale says when you wake up in the morning after you've used the toilet and before you drink or eat anything.
Another thing that helped me lose weight is not eating 3 hours before bed. I saw immediate results when I did this.
Like buff said it's a lifestyle change. Make sure also to get enough sleep as this can make us gain weight or make weight loss difficult, look it up its true.