Why can't i lose weight?

I'm 21 years old, 5'1", and 118 pounds. I work out an hour every day doing hard cardio, strength training, and ab work. i eat really healthy, take vitamins and never eat fast food/refined sugar/saturated fats, but i'm not losing weight! i've been trying for the last 2 months and haven't lost a single pound. I have a fair amount of muscle and am pretty toned, but i haven't lost any weight, at least that i can tell. what's going on?