Any other girls out their having problems losing weight?

I go to the gym three times a week. I drink nothing but water. I make sure I est very healthy (salads, low cal, low fat, whole grains, etc). I know that I could be gaining muscle, so I don't really pay attention to the number on the scale, even though it never, ever seems to change all that much (I fluctuate within 5-7 lbs), but it doesn't seem like my body fat is going away. I still look tubby more than fat. My stomach still looks big. My thighs are still so thick. I just don't know what to do.