In my opinion, yes get her tested.
She is showing some symptoms of CF, and if it is the case, you want too catch it as early as possible. IT sounds like you've really done your research into things it could be. Try not too worry about
those things for now, get your daughter tested and then go on from there.
CF very rarely shows up in family history. The only person in my family I know has it, is my brother, my sister managed too escape it. Noone else, as far back as we can follow has had CF.
Sometimes people don't desaturate in oxygen levels, this can be normal. I can be all puffed out, gasping for air, coughing my head off, nails turning blue, and my levels will stay above 95%.
With regards too pooing a lot, it matters a lot aswell what the stools are like. If they are loose, orange or yellow and greasy, then this could mean CF too.
With regards too salty taste, this is a typical sign yes, but you cannot always tell. My brothers sweat test results are on the lower end of the defintely CF scale, salt will collect in his hat sometimes, but otherwise you can't really tell. Me on the other hand am at the very high end, find salt crystalises on my arms, and I sometimes even get salty saliva. If I hold someones hand and they have cut, well they know about
it pretty quickly. But as I say, my brother has never been this bad.
Get your daughter tested for your own piece of mind, and then go from there on what else could be causing the symptoms.
Best of luck, and let us know how you get on:)
PS, your English is excellant! Let me know if there's anything you don't understand.