I agree. It is very frustrating and we constantly adjust. My son's A1C went up too after a year or so of diagnosis. I just keep reminding myself that his body is doing things we can't account for all the time and that he will go up and down and move around based on his hormones, growth patterns, holidays, eating habits, school, stress, activity level. All I can do is work to accomodate, adjust, and ensure I keep him as close to range as possible.
One thing I am working on is his Lantus or long acting insulin. We use such small doses on a daily basis that we don't go through a bottle in a month. I believe the insulin is not viable for a full 28 days and that it is more evident in a child like mine because his system is very sensitive to insulin. We always have trouble the last two weeks of the bottle which tends to throw everything off for us. I have started just this month to swap out my Lantus every 14 days instead of every 28 and so far this month his numbers have been better. Especially at night which is when we have creeping issues. Not sure of your situation but may help.