How come when I try to get a girlfriend they always say no because of my disability?

I am 18, I am always on the lookout for a girlfriend, but every time I go look and talk to them they automatically get put off from my disability. I am wheelchair dependent but still look healthy on the outside of my body. I have an immune deficiency which has done damage to my lungs so I wear oxygen. I have severe scoliosis but it is rarely noticeable. No matter which girl I talk to they always don't seem to care. I want a family when I am older but no girl who I ever talked to have hearts. Why do they not like a person like me?