Checking the theory? Newly Insulin Dependent Type 2 :)

Ok, just want to check the theory (and medical advice) I have going right now... Please bare with me.

My pre sugars were 7.0mmol.

I had two bacon and egg sandwiches on Linseeded Bread.
The total carbs in the meal were approximately 47g.

So I took 5 units of Novo Rapid. (to cover this particular meal)

(Ps.) I also have 18units per day of Tresiba long acting injected in a morning - how would that factor in mathematically?

Is this a good way of working through everything I eat? - P.S. - I'm **** at maths so any replies in simpleton terms please

Thanks in Advance.