Hi Kathryn,
I had always thought that I would never be able to have biological children. It wasn't until I found this web site that I realized that there are plenty of CF women having children and that it is a possibility. But only you, your fiance, and your doctor can decide if it's a good time for you to carry a pregnancy. It depends on how stable your health is and many other factors. It sounds like your doctor is supportive of your decisions and that's great to have. My doctors were the same and told me the risks and that it's not ideal for a CF woman to carry children but that many people do it with no adverse consequences.
For me, my FEV1 was around 85-95% prior to getting pregnant and I was considered a normal weight. The pregnancy went wonderfully and I was monitored very closely by a high-risk OB. I was very fortunate to not have developed gestational diabetes (because it happens to about 50% of CF women who do not have CFRD already). I did have an exacerbation about 4 months into the pregnancy, but that was fixed with some colistin. Luckily I did not require any IV antibiotics. I would have been a little afraid for the baby if I had to do IV's while pregnant, although I've heard that many are safe for pregnancy. I took all my regular meds which included inhaled Tobi, Pulmozyme, enzymes, and vitamins. I had an incredibly fast labor of just a few hours and pushed for 30 mins. It was such a great experience!
Following the birth, the baby was colicky, ate irratically, and slept horrible. Breast feeding was a nightmare and I had to give that up within the first week. I was terribly sleep deprived and exhausted. My FEV1 at 3 weeks postpartum was down to 65% and my weight had dropped 20 lbs from my pre-pregnancy weight. My doctors weren't sure if I would regain my lung function since some women don't after pregnancy. Luckily with the baby sleeping and eating better over the months, I gradually got more sleep and started eating better. My PFT's and weight are now back to baseline.
I'm still a bit tired now since the baby is still getting up once a night to eat, but overall life is calm now and he's 5 months old. I'm thrilled I got to experience it but it scared me to think I may have gotten sicker from having a baby. But the experience is something I will never forget.
I hope you will be able to find the route that works best for you. Good luck and keep us updated.