Diet and losing weight advice please?

I'm 5'5 and 120lb but I've been working out a solid month. No weight loss, but half an inch off my waist, bust, hips. Actually, it may be as much as an inch off at this point. I'm in my second month of exercise and I'm working out for longer periods of time (50min instead of 30). I have thunder thighs and want to tone this part of my body, as well as my arms and stomach. My question is, if I want to see results should I begin dieting? I pretty much eat whatever I want, but not enough to go over the daily calorie intake. So, in a way I'm maintaining my weight. But most of the time I don't eat too much, so I should lose weight anyway. Um, I know this is weird but what if I ate yoplait yogurt in the morning, yoplait yogurt and a salad for lunch and guacamole and chips for dinner? If I did that and worked out an entire month would I lose weight? And if I did lose weight, would this weight stay off if I began eating whatever I wanted again but continued exercise? Thank you everyone who answers.