It sounds like the material does not come easily to you. Whether this is due to your illnesses or it just isn't your thing, I really am not sure. That would have to be something for you and your health care team to figure out. Is this your passion and what you want to do for the rest of your life?

That being said, have you looked into different programs that interest you just in case this is not your path? Perhaps some of the credits you have would transfer into this new program.