i've been in the same boat too. When I finished high school I hung out at home for a couple of months and gained quite a bit of weight from bordem eating. Ended up around 160lbs on my 5'9'' body. Working at summer camp brought me back down to 150lbs, and then at college, being on a regular diet and being active I came down to 140lbs. But it was always more fat than muscle. Now that I'm training I'm usually around 130- 135lbs, but I too get worried about my thighs and butt.
But the other day my BF was complementing me on how hot I look now that I'm in such good shape, but said he liked my butt... told me not to lose that because it looks nice the way it is. Besides, in Montreal I'd freeze if I lost anymore fat!
Don't forget that fat gives us those curves that are so attractive, and that women need at leat 10-12% body fat to maintain proper health.