I can see a number of potential pitfalls. Let's start with the three most likely:
1) You just haven't been doing it long enough. I don't want to belittle your efforts, but it takes years, not months, to build the body you want. I'm sure if you speak to any woman on here who has the sort of body you're after they'll tell you of similar problems they faced when younger and how long it took them to finally start to get the body tight in the right areas. The problem with bodyfat is that the first place you gain it - hips/thighs if you're female - will be the last place you lose it from. So it won't be until the rest of you is starting to look like your ideal that you'll finally see those changes in your lower body.
2) Portion sizes. Your comment that you "bulk up easily" worries me. In my experience the only women who bulk up easily are those who put too much food on their plate. If you don't know how much you eat, and by this I mean down to the exact gram of protein/fat/carbs, then you have no idea whether you're eating the right amount for your body. Start by weighing your food, keeping a food diary and doing the math for how much you are actually eating. If this sounds like hard work it is. But then again, no one said looking great is easy.
3) The type of training you are doing could be wrong for you. Many women get stuck on programs designed by men who have no real understanding of the major differences between male and female physiology. A program that works for a man can end up being a total disaster for a woman.
Hope that helps. And welcome to the board!