How to Get More Muscle, and a 6 Pack Abs?

I need help with getting more muscle and i want to get a six pack abs. But idk how to get a six pack abs. I have a deadly disease called cystic fibrosis so i cannot afford to loose fat (only about 14% body fat) because if i go to the hospital my body will need the fat to eat off of. So i just need ab exercises, but extreme ab exercises to make up for not loosing body fat. Also how do get toned?

Suggestion:

work out and eat a max of 2000 calories a day. good luck!