i don't know what to do

I have had off an on eating problems for a couple of years now, and though i am not clinically obese i can see myself gaining more and more weight. I'm only seventeen years old, and though i have tried time and again to overcome this illness nothing wil work - i know if i continue on this path i will encounter health problems later in life. Most recently my problem has been compulsive overeating, I turned to my family for support but since i am not very obese they attribute it to just being a teenager. I don't know what else to do ... if anyone could offer some help i would greatly appreciate it.