Unfortunately -- yes, I think you should continue to push for full genetic testing. Too many people on here with sweat tests in the 20's and 30's -- I think it would be irresponsible for an experienced CF doctor to not want to pursue testing.
The key phrase here may be "A-Typical CF". Tell the doctor you want to rule out CF - even though "the chart" says it is in the normal range, in my book it's still elevated -- the sweat chloride channels are still not functioning quite right if she's up that high. I think the people who really get a clear "negative" are the one's with single digit numbers.
I have seen people respond on this board, who have confirmed genetic results say their sweat test number is as low as 14, most reporting in the 20's and 30's.
You may have already told us this but I don't remember who is who anymore - there are so many new mothers on here in similar situations right now.... was the sweat test done at an accredited CF facility? Is the doctor you are scheduled to see in October a Pulmonologist at an accredited CF facility? You can find out if you are at a CFF center by going to www.cff.org and clicking on find a chapter then find a facility, then type in your zip code.
It's a tough spot to be in - I'm sorry to hear you are there. Please keep us posted.