I was diagnosed at age 20. Growing up I always had sinus problems (had 2 surgeries when I was younger), asthma, and had pneumonia as an infant. I was classified as "failure to thrive" at birth, but sweat tests were inconclusive and doctors decided I did not have CF (this was before the gene was discovered).
My sophomore year of college I got a nasty case of bronchitis that never really went away for a year. I started researching CF and saw that there have been cases of late diagnosis, so I demanded to be retested. My sweat test came back just barely positive and genetic test revealed that I did have CF (G542X/R117H).
The only noticible difference is that I'm not coughing up tons of green stuff anymore, like I was the year I was diagnosed. I am very compliant w/ treatments and exercise, and am still "healthy." I have had a couple instances of lung inflammation, but they were quickly resolved by steroids.
I had a lot of constipation (or maybe blockages?) issues before being dx w/ CF that landed me in the ER several times. After being diagnosed and being on miralax, etc. I have not really had any other GI issues.
You are very right; every case is VERY indidualized and different. There's my story though <img src="i/expressions/face-icon-small-smile.gif" border="0">