Having followed the standard advice of ,eating 3 meals a day and injecting insulin in the correct proportion, for more that 30 years, I know the struggle you are having to cope with. I now understand it is impossible to get blood sugar levels consistently in target with the many variations that life throws in. I got really strict on myself for about 2 years, eating at exactly the same time and the same amounts and types of carbs, I was even eating exactly the same foods ( really boring) and even that did not make it possible to get a good even BG level.
I am of course still insulin dependent but I now have fairly normal BG levels all day with very little variation through the day. How did I do that?
I did this by changing my diet to Very Low Carb. I feel sort of cured and wish only that I had discovered this many years ago.
I can only imagine the struggle that you go through day after day, to manage you son's condition. That is a really tough job and you have my total respect.
Please allow me to encourage you do the research and consider this change in diet for your son. Lots of great information on this website and many others.
I share this with you as i am honestly sure it will make all your lives so much easier....and more healthy. Best of luck and my best wishes.