You can do this and you will.
I've never been a normal weight in my adult life. I will sometimes go off on a worry tangent "What if I never make it? How do I know I can even do this since I've always been fat?" but with support, and an honest commitment I wake up and realize I CAN and I AM.
You can do the same. Failure is not an option. If you tell yourself there is no quitting, there is only continuing to eat heathfully, then that's all there will be.