You are making it tougher on your self than you need to.

Fill the tube to the 10 ml line with pool water. Add your FAS-DPD powder--one scoop is enough if it turns a rich pink.

As I add each drop I swirl and count as follows:
".5, 1.0, 1.5, 2.0, 2.5, 3.0,.....15.5, 16.0" as need be.

I don't count the drops ("16.0" would be 32 drops), I count what the FC level is when it turns clear. No math, no dividing, no calculating. I just have to be able to add by .5.

Then, when I run the CC test, I count the same way, usually...".5" and I'm done.

It's possible your daughter has picked up a dose of Noro-Virus (what used to be called stomach flu till it hit the cruise ships and got the longer name "Norwalk Virus").
Getting her to a doctor would be wise.