There are some formulas that doctors use to estimate the starting insulin for newly diagnosed type 1 diabetes. But then it is usually adjusted. Some books will state what the 'average' is, but it's just that, an average. You need what you need. I take about 1/3 unit per KG. If you eat more carbs or are less active, you will typically need 'more' than average. If you have 'insulin resistance', you will likely need more.
The question is - are your BG levels within range ? Are you too high or too low often ? That's how you know if you have the right amount of insulin and food.