I haven't used Novolog, so don't even know how long it is active, but I think it is one of the fast ones, 4 hours?
I'll give an example with Humalog, which works well for me. It acts over about 4 hours.
If you think of the blood sugars and the insulin as bell curves on a graph, the curve from the sugars entering the blood will be high and short if it is a carb meal. They will be in the blood in about 1 and a half hours.
The Humalog entering the blood will be a lower, longer curve, about 4 hours. At the end of 4 hours, if the insulin has matched the meal, your bg will be back to normal.
Also, if the insulin has matched the meal, the area under the 2 bell curves will be the same.
If you are using a slow insulin, the sugars from the meal won't be covered until the insulin has finished acting. Your bg levels will be higher until then. The insulin does not just sit in a reservoir and jump out when sugars appear.
If I have eaten one meal and injected enough to cover it, and then have another meal 2 hours later, I will just inject again, enough to cover that one too. It will be 4 hours after the second injection before everything is balanced out.
This communication stuff isn't easy, and to me that's normal. It often takes a bit of back and forth to get at the key to a problem. If things aren't clear this is one of those areas where it is worth the effort to get them clear.
best wishes,
lia