As your pancreas is making plenty of insulin I would think its unlikely that there is anything wrong with your beta cells.
If your HbA1c is deteriorating, it is more likely that your insulin resistance is getting worse. Although a rise of just 0.4 of a percentage is probably well within the margin of error for a HbA1c test.
Even if the rise can't be explained by the accuracy of the test your HbA1c is the same as mine but you are managing to eat more than twice the amount of carbs I do. I think it's probably a little too soon to be worrying about beta cell burn out.