huge thighs

I am 18 & am a first year college student. i'm doing very well in my school work but weight is kicking my butt. i know they say everyone gains the freshman 15 but i went to school weighing 130 and i'm up to 155. i know this isn't fat or an unhealthy weight but it's not me. it's not my size. i don't notice the weight anywhere else but in my thighs & ive had to sell all my pants because nothing fits anymore. i'm constantly wearing leggings or sweatpants and i'm over it. i just need help figuring out how to slim out my thighs and keep the weight off... please help