I'm not sure about what you read - I don't think feeding every 3-4 hours is going to increase her blood sugar. I fed punkin at preshot and +3 - then he went til the next preshot with just a couple of bites of chicken breast. Most people feed most of the food in the first half of the cycle so that you're not feeding a lot in the second half when the insulin's strength is waning. Eating too much in the later part of the cycle can put the brakes on your insulin action.
My doctor has said that for people, when you fast for a blood test, you should fast for 8-10 hrs rather than "longer is better." After about 10 hrs your blood sugar will begin to rise. Not sure how/if that would apply to cats, however, and i certainly don't think your switch from 3 to 4 hours would cause higher numbers. I just think Zoey isn't to her right dose yet.
So work that juice, miss Zoey!