I know I'm not a parent, but I just thought I had something to add.
Having a baby is, and should be 100% your decision as parents.
I will say just consider every possible outcome, what if this child has a worser case of CF from the get go. Also, a lot of people don't consider the fact that a few people with CF, don't get ill until they're around 16/17, then all of a sudden their health will plummet, without rhyme or reason.
It's not selfish of you for wanting another child though, it's human nature to want kids, to see them grow up into their own person. At the end of the day, noone knows exactly all the genetic faults that they are carrying. If poeple worried about
what genes they were passing on etc. The human population of the earth would be zero.
I'm currently in a situation myself where someone with CF on one of the forums I go on, has passed away. Leaving behind an 8 month old baby. That's the thing that's making me stop and think. Not whether or not I will pass on the CF gene. Because even at my worse, there's always a part of me that knows inside it's not always going to be this bad, there will be a rainbow, I just have to look for it. Noone can know 100% if they have the gene, due to there been thousands of mutations, and they can only test for a handful. To be on the safe side, noone should get pregnant. But that goes against all our intincts as humans/animals.
I've met some very amazing people with CF, out of everyone I've met, only one that I know of has been put in prison. I think the CF gene definately adds an exra sparkle into a person. I'm sure the gene for strength is located right next door to the CF gene, and they are neighbours that get on well together.
I have one friend who was given a year to live, a year on she was still batteling. 4 pnuemothorax's and a haemothorax in the space of 2 weeks. Her family were given the talk, that they could do no more, it was now upto her. While all this was happening, she was on TV a lot, to try and raise awareness for organ donation. Started an organisation. She then did something truely amazing, and was pushed round a racecourse with hundreds of others and about 50 of her angels, then, on full oxygen, she got out and walked the last 500 meters with this great huge cheesy grin on her face. The physios had said she'd only be able to manage 100 meters.
She did lots more awareness raising on TV. God only knows how! Then 6 months later, she got a double lung transplant. But the lungs were out of the body for more than 5 hours, normally meaning they would be unusable. They went ahead and fitted them anyway, it was her only chance of survival really. It meant she started out with a frozen diaphram. Had to be taught how to walk again, after been chair bound/sedated for so long. 2 months after her op, she was running down a beach. Then she got a job, like she'd wanted. While ill she'd done a lot of studying at uni etc. Then she managed to get her organisation turned into a charity and won an award for it.
There are a lot of hard and bad bits to CF. But, it definately wakes you up, and helps you appreciate life more.
One not-so-wise women (my gran actually) once said to me, that all people born with disabilities, should be killed at birth, so they don't put as much strain on the economy. It's so easy for her to say that which is disturbing, but you know. In my 22 years of life, I have done a lot more with my life and helped far more people, than she as ever done in her 61 years. I personally think someone should kill her, as she sits on her bum all day eating, then throwing what she's eaten back up (she's had a gastric bipass free on the NHS, because she couldn't stick to diets.)
You know, this is your decision, and nobody, not one person should make you feel bad for it.
Sorry this has turned into quite a long winded rambly post.
Hope you and your children stay healthy.