I find that weight sometimes settles in different places at different times--and one's body as a teenager is different from one's body as an adult.
That said, exercise is very likely to be the difference. Were you more active as a teenager than you are now? Muscle is more compact than fat, so if you were more active and carried more muscle, you'd look a bit leaner than if you didn't.
"Losing weight is easy; I've done it dozens of times."
(with apologies to Mark Twain).
Ultimate goal: Size 10 clothing.