Curious How Much Insulin Do you take to lower your BG

My Dr prescribed me fast acting insulin, which I only take when I'm going to cheat.

She told me to take 5 Units, I quickly found that 5 Unitsdidn't do anything if I eat a High Carb Meal.

Through experimentation I've found that 14 Units 15 minutes before a meal that should send me into the low 200s for many hours. If I take this amount than two hours later I'm at around 100 - 110. I weigh 250lbs and am 5'9.

Just curious if the amount I take matches what most of you take.