Insurance wont cover gastric byp.. So what now? Help?

im 19yrs old and im on my fathers insurance humana.. I want to get gastric byp but WLS is not a benefit on my dad policy or even offered at his job the insurance company told me that and i really want this surgery but do not have the money to pay for it. I am 5'5 and weigh 315lbs.. I have tried diets and everything and been to doctors for weight.. I always been obese since i was like 6yrs old. Is there anyway i can get my insurance to cover it? Has anyone else had this problem.. Please let me know im in desperate need of this. Thanks