I know a girl who is 17 her little brother was diagnosed with CF but he is only her half brother and as such has another mom. She ahs never been tested for CF. This girl has had a very slight, soft cough most of her life. It's not very frequent but it comes and goes... no hacking just a soft cough. Although at one point in her life she ended up coughing up blood. She rarely gets sick and is in great physical condition. Also somtime she has trouble passing her stools and will take laxitives. She has a ton of energy and does not get tired easily or have much trouble breathing, though. Is there any chance she does not have CF and if she does is this just a very mild case?