This is the problem of imprecise science of Food and Nutrition, especially when you are within the range of margin of errors.

Let me make an example;
According to USDA web site, a medium size Pear is 178g.
103 kcal
0.68g protein
27.52g Total Carb
17.44g Sugar

If you eat pear before, you know;
Some are sour, some are blend and some are sweet.
The sour one might have 5g sugar
The blend one might have 17g sugar
The sweet one might have 50g sugar

Since your personal margin of errors are tiny, you might want to count calories and increase your gap.

Let's say your desire calories is 2000kcal, you can try 1800kcal which would cover 200kcal errors.

I hate to see people giving up low carb because some bibles do not work.